>> . . . there's no standard factory reset . . .
PS: In the diagnostics mode there are two functions (1) to do a reset of the all data [basically User presets sequences] and (2) to do a reset of all the data except the sequences [basically just the presets, but not the songs and patterns].
E-loader is needed to update or reload the OS.
Just like the 1 RU P2K variants, powering up while holding down the two cursor keys will get the CS/P2500 into diagnostics mode. I believe the data reset functions are at the end--not sure what the numbers are.
Doing the full data reset [initialization] replaces all the sequences [patterns and songs] with empty sequences. That's why the factory sequences are available in zip files. E-Loader 1.1 has the ability to transfer sequences between a PC and a CS/P2500. Using usb transfer is much faster than midi transfer, but with the right cables and the proper setup/PC/OS. Both should work.
If your acquaintance has problems with the transfer, someone here should be able to help diagnose the issue.