PRS-600 with 1.04b Boroda version. Installed the hack to have the clock.
I must admit the process had a heart-stopping part:
When I disconnected the USB cable, the reader started the memory scan (that is quite lengthy in my case as I have more than 600 ebooks loaded, spread between the main memory and an 8 GB SD card.
As there were no warnings in the instructive I pressed the reset button while this scan was still in process and... the screen froze. This is somehow expectable, but after some 5-10 minutes no changes were evident, so I did the normal shutdown procedure (3 seconds with the power switch slided to the "on" side). No reaction.
Reset again. Again nothing.
I removed the SD card, thinking that perhaps something in the startup-update routine could be confused because of it.
Then I did as I should to turn it on if all were OK. (again 3 seconds with the power switch slided to the "on" side). This time the LED started blinking yellow, with the screen still stuck in the same image as when I reset the unit. It kept so until about 10 minutes later I decided to try again a "shutdown". The LED turned off.
Again turn on, and this time the LED blinked for some minutes and then I saw with relief the screen had changed to the usual "boot" one.
When it finished scanning the library, it booted again by itself.
After this the unit started OK.
Whew...
It has been almost two weeks since the procedure and the reader is stable and working well.
If there's a next release and I dare to again risk a stroke I will remember to take the SD card off the reader just for a good measure.