The board doesn't do DHCP at all. No 192.168.88.0/24 network either. This is for the
RB750UP

Also the wireless was disabled too. So I have a locked up box with no access currently.

Maybe I can change mac addresses and it will work?

As far as I can tell it didn't loose dhcp, but the problem with dns address redistribution which was fixed in 5.15 reintroduced.. Very annoying

For some reason, after I reset the router...

I can't connect to the WIFI, it's turned off
I can't connect to the box, I get a 169.X.X.X ip each time, all ports 1-5

I reset the router but the new routerboard software seems to not work
with this hardware.

http://forum.mikrotik.com/viewtopic.php?t=43462&f=13

That post helped a lot. Purchased Cross-Over Cable, connected to port 2
Winbox connected via Mac Address, Layer 2
Tweaked the box for awhile, got DHCP working again, Layer 3

And learned a whole lot in the process.