I know I know...
bloody heretical I am
can't say I haven't enjoyed the "need for speed" with fap...
but the windburn I get ends up with me crashing and burning...
or it used to anyway..
haven't used fap in some time now...
maybes it be all betterses now ...huh?
could be...
someone want to test the piranha infested fap waters with their unit?
Me ...
I'm keeping my unit firmly zipped up in mah pants and goin' no where near that pool with mah unit danglin' out..thas fur shur

whats with the charging issue ?
did you flash the phone ?
if so did you flash emmc too ?
san you connect the phone to pc via usb cable in mass storage mode and transfer files ?
what exactly you are using to charge the battries inside your n900 i.e the normal way via a wall outlet ? model of the charger or better is it 1amps ?
lastly observe the notification led while you plug in a charger and tell us the pattern also do you have acces to a multimeter as you comfortably put to use crocodile clips to charge your battries externally.

All this to diagonise your charging problem precisely .
answer them in sequence.
thanks

so,
about HAM, it's fine for me, I used either hildon and maemo.org app without problems until the battery problems, and I think I'll continue (however Fap could be cool to test too)

the charging issue, I'm still stuck with it, I'm charging the batteries again and I'll see when I have all of them at 4.2V (one of them is a 4V for the moment)

I did not flash it (I planned to do so but the USB problems prevented me to do so)

nor the emmc

mass storage mode, it worked for five seconds (the phone asked what mode it should enable) and after that, it shut off.

I used three devices, two with internal charger:
a port on my PC and a 500mA charger (a bit crappy) and also the TP4056 external lithium charger.

the notification led, it's a bit random but either it stays yellow, either it blinks yellow or sometimes it lights up a tiny little bit red, that's when the phone is off. When it's on, it says "charge defect" or it get stuck and shuts off.

About the multimeter, I have one (standard 30$ model, decent but nothing fancy), I also have an almost complete electronics "lab" (but I'm not much in this kind of tiny electronic devices (I'm starting at soldering SMT simple components, that's the most advanced I can do for the moment)

looks like your n900 will be allright

I just charged all the batteries I have, firstly the phone didn't want to wake up, then I started unscrewing the LCD, while holding the battery with one hand, I pressed the on button, the phone booted fine one/two times, when I screwed everything back, it didn't want to get on.

Conclusions:
-It works
-there is a charging and probably a battery contact or sensor problem

I'll investigate further, does anyone knows if there are sensors (maybe hall effect) that may prevent the phone to start (like a back cover detection system or something like that) also, I noted that the phone starts more often when the LCD mechanism is open, are there any reasons ?

Thanks in advance

wow ..
messed up man.
yeah ...
pretty much all nxx0's have back cover "not on" or "not secure" detection sumthin'-sumthin'....
meaning it doesn't like to boot if the cover is not in place.
Lil' magnet I think it is..(visible) in the kickstand (specifically on the n900) ...

If my mem. serves....
I could be confusing the magnet with some other purpose....
but I seem to recall that was the purpose of it...

pay no attention ...
pichlo is correct in the purpose of the magnets on the nxx0's...
I recall that now...

Did you also try to replace the LCD block again with the original one? I haven't had any of the problems you've described so maybe replacing the LCD block did trigger something?

The purpose of that magnet is to automatically unmount the SD card when the battery cover is removed. It does not prevent the device booting, nor does it force it to shut dovn. Your problem may be with battery contacts or, worse, a headline crack in the PCB.

There we go!
I knew it was for something important!
Thanks pichlo...
my brain must be addled from all the nog and rum...
argh.
now that the season is done it is time to sober up and regain my brain...

open it up clean everything with isoprophyle alchol or similar
brush all contact points in board with a needle do not forget connectors like the display and touch connector and clean the battrey contacts good bring them a lillle closer ,clean the usb port
lastly post multimeter readings here check throughly start with battrey contacts and usb subsystem.