Unbricking - natowi/prs-plus GitHub Wiki

PRS 300 / 505

If your PRS 300/505 stops loading at the "Reader Startup" page, or cycles thru restarts follow this steps:

press the reset button on your reader
flip the power-switch and immediately connect the USB cable. * if you can get normal access to internal memory (IM), try to backup your files, run CHKDSK on IM, or format IM (FAT) then disconnect from USB an see if it is starting again. * If a external device with one file "Protected!!" shows up continue with step 4;
if no device shows up, there is the 10 times reset method: reset the reader, power on, reset when the Reader Startup-Screen is shown, repeat this 10 times, then a message like "firmeware update failed, update firmware now" will show up. With this message shown connect the reader to USB and follow the next step
fire up the appropriate updater (see links below) and follow the onscreen instructions (a Windows-PC is needed for this operation)
only for the 300: According to boroda's (aka porkupan) manual, in case of recovery firmware, only 505's updater is available, it brings device (300) back into state from where you can try to reflash it again with proper prs 300 firmware.

There is no simple way to unbrick.