As a last thing to try, you could try the downgrade/reinstall via flashdrive, since it does not depend on on-screen display (i.e. put update.zip on the flashdrive, plug it in while the PE is turned off and hold the right button combo while turning on, and the blinking activity light on the flashdrive after a while should tell you whether it is being read from)

Also, sometimes the amount of time holding down the power or reset button on some devices makes a difference, so make sure you hold it for at least 1 minute to be sure.