First of all, as I said in my original write-up, I am not just gluing the USB port to the lower PCB alone. That would not be strong enough. I am encapsulating the USB port in epoxy, and using the heatsink behind it, its own solder points, the upper PCB, the upper PCB plastic support, etc to strengthen its adhesion.

And I actually did the test you suggested. I took an old SODIMM stick that visually has a PCB almost identical to the N900 (the green mask is identical, same types of components spread around, etc). I applied blobs of epoxy at random over its entire surface.

Some epoxy blobs covered memory chips, others touched the solder mask and metallic connectors, yet others just sat on top of the solder mask with no contact to anything else.

After letting the epoxy cure for less than 1h, I tried removing one blob that was covering just the solder mask. It was purely sitting there, not touching any components, memory chips, traces or metallic components. I had to pry it off with a screw driver, applying so much force that I would have ripped off your solder job and the USB port with it.

Yes, I know epoxy is not ideal under these circumstances. But I'm willing to bet money that properly epoxying the USB port will be just as strong if not stronger than resoldering two contacts. And I did not point this out before, but you only really strengthened one side, the other is just as weak as before. To get to the other side, you would have to take the upper PCB off, which I think is impossible without ruining the sticky foam and who knows what else.

Lastly, this is the epoxy I used: PermaPoxy General Purpose Epoxy Feel free to test it yourselves before disassembling your N900s. Just make sure you follow the instructions on the back of the packaging regarding mixing, etc.

Update: It is now about 12h of curing, and the epoxy strength is identical to that after 1h of curing. But draw your own conclusions guys...