If it worked once, then BIOS can support the keyboard (which would most likely let it work in DOS as well)
Obviously something has changed ... try resetting BIOS to a clean setup (make sure to note drove types and anything else you might need to re-enter in BIOS)
Mouse "freaking out" is a bit worrisome ... perhaps you have a hardware failure (although if mouse partially works, I'd expect at least a little response to the keyboard)
- Dave ; https://dunfield.themindfactory.com ; "Daves Old Computers" ; SW dev addict best known:
ImageDisk: rd/wr ANY floppy PChardware can ; Micro-C: compiler for DOS+ManySmallCPU ; DDLINK: simple/small FileTrans(w/o netSW)via Lan/Lpt/Serial