I got an eBay n800 that refuses to boot fully. or charge. It'll occasionally make it into maemo only to whine that the battery is low and shuts off again. I don't seem to be able to change it no matter what I do... This is my first maemo or Nokia on general device and I'm excited to play with it. Pics attached.
imgur.com/xqRCRqs,uJhurJw

get another battery..
for sure sounds like that one is beaten...
turn off your device and plug it in the charger..
charge it fully..
if the prob still persists ...it's the batt.
the os may "never" been reflashed...which could be adding to the prob.
but with a proper new battery...[even a recently purchased original official oem bp-5l that is old.. may be in fabulous shape...I have 8 official original bp-5l's 5 of them came with the n800's I bought...three didn't ...all of them I have been using ...some for a looonnng time now...half a decade + ...and none of them are below 94% to this day...good track record...]

once with a battery that will charge and keep said charge properly...
I would suggest immediate reinstallation of the os.
then of course clone the base [latest and last os.. with no tweaking...] diablo 2008 for n800 [from the internal "on device"] to a sd card in the internal sd card slot...then from that cloned base os on the internal card...install cssu, telescope, asui, ...diablo turbo [the most recent uber tweak for the n8x0...] and then you will find your battery and your system can be optimized to the ~nth degree ...
you'll be laughing...

i was afriad i was gonna be told it was that.. Do you know any reliable places to get a decent battery? And i will probably be posting about how to do that second part.. i have very liuttle linux background.. just want anohter fourm user tvall(http://talk.maemo.com/member.php?u=70253) has taught me. so this will be a interesting experence

possibly this ...never tried it soooo....caveat emptor...
http://www.ebay.ca/itm/NOKIA-Battery...item5663732720
but I would trust this more...
esp. for the price...
http://www.ebay.ca/itm/OEM-GENUINE-N...item43ca9636de

currently there are not a ton of n800 batts available on ebay...but that changes all the time...

up to you..
there is also the possibility of taking a beaten battery and turning it into a dummy batt and using say this...http://www.ebay.ca/itm/141082066753?...84.m1436.l2649
and then you would be free of batteries ...

As far as "how" to do wizardry hocus-pocus al-a-ma-focus stuff...
[or as we here call it..."the norm"] if you are not used to linux or maemo for that matter...
there are many "how to's" ...
hell I did a pretty comprehensive how to...
from flashing ...step by step...for the compleat "newmo" [tm, patent pending] like you... to go from absolute ignorance and yet still end up with the zippiest most tweaked out device that can possibly be done...
in fact to make it even easier...
instead of reading..
I included numbered video tutorials..
there are plenty of choices for you in our forum and wiki here...

You remember how I told you that bit about cloning the entire os from the device onto an sd card ..and then running your system off the card?

I just took a look at your 1st post ...
in particular the pics ...
your 1st pic. says a 1000 words.

Whoever owned the device previously had the system cloned to an sd card...hence "failed to boot from yada-yada [sd card]...commencing booting from flash [which is the on-device os]..."

removing "that specific sd card" will mean that the "boot loader" [fancy term for the program which asks you or is automated to decide which partition[s] on either the device or card to start-up from...and thus load up that specific operating system..] cannot find the card [since it has been removed from either the internal or external card slot where it should be...I believe it was set to boot up from the internal card slot...the "i" in "immc2" is the give away...]

If with your ebay purchase there is an sd card which came with it...which is not installed in either the internal or external card slot...put it in and start it up...it should find the os on the card and you are good to go.

Doesn't solve your batt. prob though...gotta get one...
also it is possible that the "not charging" culprit is the charger [possibly...though doubtful...] or the n800 charger port [yet again doubtful but possible...] not connecting to the charger pin..
Considering the fact you do not know the history of the device...
Check for how loose the charger pin sits in the n800 charger port...
check for abrasion or wear or damage on the charger pin or the cord or the charger block...
Check for damage or crud inside the n800 charger port...
It is possible that any of the above may be the case...

I have found in my time...as I have just recently stated elsewhere here...that the standard rectangular shaped nokia charger has quirks which I found rectified once I changed it over to the more square shaped nokia travel charger...which works admirably...

If you don't have that specific sd card...or it didn't come with it...
no worries...once you have a battery ..you can scrub the device ...reinstall the os onto the device ...clone the os to a new card and start having fun...

So you were right! i ordered another battery and it booted normally! booting without the card took me to a stock build of OS2008 (i think) the card took me to a custom build with the previous users stuff on it. now my question is where do i go from here.. all the f;ashing guides are for osx/linux.. i have a custom built desktop that doesn't play nice with Linux...

good.
sussed that out ...
now...
"custom os on your desktop pc" doesn't illumine exactly what you are running.
sooo...
what are you running?
what you are running will tell me what kind of help I'll be or whether you will need someone who is savvy in your particular os.
win of some kind?
mac of some flavour?
linux?
bsd?
gentoo?
another source based linux?
something odd or unlikely or rare?
I've messed with and run a few obscure os's...


If you want to fart around in your particular os and try to get devices/os's to recog. each other .. go for it.
I can't help there..

otherwise
easiest, simplest, most prob free suggestion is..
don't muck up your custom whatever...
install vmware...
install win xp or 7 [can be libusb persnickety ...] ...
or install buntu ..or debian on the vmware and you shouldn't have any probs from there...there are explanatory guides better'n me... out there for that ...

As far as help goes...
the walkthrough in my sig ["pimp my n8x0"] ...
is as easy as it will ever ever ever everevervreevr get.
You will not find an easier to understand guide...
nor a more comprehensive guide for the n8x0
and there is the video walkthrough as well.
Just follow exactly what is done.
There is nothing confusing or hard about the walkthrough..
just pick what outcome you wish and use the described methods to achieve it.
The walkthrough and vids initially deal with the simplistic gui of nokia's software wizard which works for xp and win7 to flash the firmware...[I used xp and win7 for the walkthroughs since most who come to maemo are coming from M$...]
after flashing... it is universally the same process from that point on concerning tweaking your n8x0 ... regardless the os....so your custom pc os has little bearing after that.