I just set a admin password for my old dlink dir655.

Oh, you'll need to restart, sure

Now this fucking thing is stuck in a bootloop and I can't get a new one until tomorrow.

You don't have to get a new one if you happen to have some free time.
The thing probably has, like most routers now, a recovery mode that allows you to reflash. But first give the 30/30/30 reset a try, should reset everything to factory settings.

@Lennerd Yeh, tried resetting it, and it actually does boot but later crashes.

Can see the login screen but nothing happens when trying to login

@ralnivar Now if you happen to not have a life you can open the thing up, find a serial connect or and get a Linux terminal.
Or you can get a new router.

@Lennerd ffs, got everything setup and now it decides to work

Maybe power delivery issues?