Mine doesn't even start flashing the eMMC... Guess there's some driver malfunction... Tried to flash firmware after that, went well, boots into the original Maemo 5. (RX-51_2009SE_20.2010.36-2_PR_COMBINED_MR0_ARM.bin the most recent? A good basis for PWNPHONE?)

Do I need the PC Suite driver for this to go well? Not sure if it has that driver, trying to find out now...

-edit-

So this is what happens (I'm hesitant to continue, don't want to brick it yet):

I enter:
flasher-3.5.exe -F RX-51_2009SE_10.2010.13-2.VANILLA_PR_EMMC_MR0_ARM.bin -f

"Waiting for device"

I'm holding U, plugging in, USB connect/disconnect sounds, "Found device RX-51 ... Booting device into flash mode.
Suitable USB device not found, waiting."

Meanwhile the N900 has the faint NOKIA logo, but doesn't have the USB logo in the top right corner. All this time I'm holding 'U'. The computer shows N900 (PC Suite mode), but needs drivers.

I corrected the driver issue, but is this the correct behavior?

-edit2-

Guess it was the correct behavior; eMMC flashed fine. Now flashing firmware...

And that went well.

To help others (and myself, because I'm sure I'll forget about this in a week)) in the future: I used this to correct the driver issues in Win7, 32-bit (yes, my 32-bit didn't accept it out of the box...).

-edit3-

Ah, I'm completely fresh and new. Now it's time to install the PWNPHONE stuff, again. Thanks for helping me solve this!

-edit4-

After starting the PWNPHONE stuff for the second time, it only needed a minute to copy all the stuff, not an hour. After that it gets you back to the BackupMenu 0.65 and errors. Guess something went wrong... Back to the lab...

-edit5-

I'm writing a book here... Anyway, I guess it installed all kinds of stuff onto the MicroSD which I didn't format/etcetera. So back to square one: flash eMMC, flash fw, format microSD, extract PWNPHONE image tarball and try installing again.