have you delete save folder and then check is the change in sys.txt work?
try to start without sys txt, if it start you can add a sys txt later
landscape or portrait, try to rotate the screen 90° and look is it start - one time happen to me, in portrait mode starts, in landscape not.
last what you can try and will work - change the multimode ini from data.
if your screen resolution is unknown- delete data zip from root, then start Igo - in portrait and landscape mode - write down the size, place data.zip file back and modify the multimode ini