Yah, that can happen if you don't get the fonts just exactly
right, I've been there myself.
The way to break the cycle is to (first take your SD card out!) do the 10 times reset trick (which is just what it sounds like: reset and restart 10 times in a row). That'll toss it into firmware update mode, then you just feed it the standard firmware (you'll need your PC for that, of course) and it'll re-update itself to that firmware.
Then you can have another go at your custom updates. I'd start those over from scratch though, since something is evidently off. The fonts are the most likely culprit there, they're pretty finicky.