Today I got my donor units! I purchased a package of two Psion 5mx handhelds - one of them does not power on, but is in good shape mechanically. The other powers up, but it doesn't open very well. The cause seems to be that is has been dropped hard, the battery compartment i beat up. It also seems that the batteries started leaking since there is evidence of corrosion (green battery terminals and discolored plastic).

The plan is to start with the mechanically broken unit and remove the keyboard. This will be converted to USB, but first I need to reverse engineer the circuit board.

I also got a Ericsson MC218, which is a rebranded 5mx. This is in very nice condition, and will be kept as is for nostalgic reasons. :) I noticed some signs of vertical banding on the display though (a design defect on these units), but I'll fix that at a later date.