Hello,
I bought a Garmin drivesmart 61 used but when I turn it on there is a white screen, I connected it with Garmin express and it is detected, what could I do? Thanks in advance.

It's got one of several possible problems, it might just be that the screen's ribbon cable is not properly fastened to the PCB connector; or the screen may have partial failed; or there's a hardware failure on the board.

Try opening it up and remove, inspect and carefully clean the contacts of the ribbon cable (use only dedicated electrical contact cleaner) then replace. It may also be that the flimsy fastener on the PCB has slipped or broken and isn't holding the ribbon cable properly. It all is ok there, try to access a working screen from another same or similar device that uses the same model of screen to test for a faulty video signal.

Ok many thanks ! I try it !!