having problems also...brand new Gt-31, got 2 days of logged data downwinding and then screen display completely disappeared. I'm not sure what has happened but suspect that i may have "steamed" it as left it on the dash in the sun....apparently a very naughty thing to do

funny thing though ...it still is logging and i've been getting the data directly from the SD card, as the only thing still working on the gps is the backlight

i've been in contact with lycosystems these past few days so i will let you know if i have any joy with it.