You make it sound like there are inherent faults with the N900 hardware that cause to deteriorate progressively overtime until it becomes a brick. This is the first time I hear of this. Is there a thread where this is discussed?

Although this is the first time I hear about the bootloader deteriorating, there are a lot of threads about the USB port falling off, the SIM contacts failing or the GSM chips needing springs to hold them to the board. I must say I have never heard of any other phone from a respectable producer suffering so many inherent problems. It feels almost as if the N900 were the unwanted child that Nokia didn't really care to raise properly.

The eMMC wearing out by repeated writing has also been mentioned countless times although I have yet to see anyone actually reporting that it has happened to them.

N900 & N9 were indeed unwanted children inside Nokia.
The first one died primarily because of focus on N97 & S^1.
The second died cause of WP7

It probably is real. However, he sold it as new, and that's misselling, at least under UK law.

Re: MicroSD, a lot on the market are no faster than the N900s internal flash.

No need to wait on CSSU Thumb.

There's an application called healthcheck which will is pretty good for testing hardware.

i am using my brand new N900...I am now a believer that few new exist out there.

You bought one from him too? :-)

What's the main difference between revision 2101 and 2204?

I have only found this condition on used phones, but flash memory does fail, the worst abuse is inadvertent instant shutdowns like dropping the phone knocking out the battery. If there is no USB access there is no good way to clear file system corruption, even bootmenu can fail if these faults build up.

The Chinese refurbs I have had access to had flash memory problems that connecting USB starting with backupmenu and cleaning up with my laptop using gparted, this phone also had issues tricking it into going to flash mode. Some of these Chinese phones will work as repaired, but dont expect a long life from a FrankeN900.
My best luck is finding real used phones in the US and EU sold by low number long registered ebay individual sellers, maybe missing some of the accessories, and are not very scratched, I assumed that they had been desk drawer queens and so far that assumption has played out.

I'd also be interested. All I know is that the USB port isn't properly soldered on any revision.

Re: Flash memory, newer memory tends to have the rewrite problem sooner due to exceeding the tolerances of the medium.

I'm not aware that anyone has had an issue with N900s flash memory.
Not sure if it's possible to measure flash degradation.

Since the OP was on an old phone, he might not upgrade very often. It's just quite plausible that if he fixes his USB and doesn't get his phone stolen, he might be using this 2nd hand(?) N900 for many years and given that it swaps even before you can open an app, it's worth considering.

IMG direct. But they dont seem to have any now. I dont like to buy from Hong Kong.