Well, I was uber stupid and forgot my lock code. >.< Reflashed and I was at least able to get back into the device. But I could not get my code back (the mtd1 hack was of no use here: the code is now encrypted...). But the libraries in charge of device locking have an interesting trait: write **** to the lock code area of where it is stored and it will be reset to 12345. Attached is a program that will do just that. Warning: It is writing to a very critical part of the N900. I will take no responsibility whatsoever if it messes up your N900. It worked for me (i.e. I was able to reboot fine and change the code fine. Multiple times, actually. I tested quite a few times.) but I cannot ensure it will do the same for you. Use at your own risk. It disables the autolock upon bootup, writes **** to the lock code area, brings up the control panel applet from which you MUST change it from 12345. Run as root, prefixing it with run-standalone.sh.