You need the Tivo & TV Power keys to program the remote for anything, so if you can't get the tv power working, you won't be able to enter a code, or put the remote into learning mode. And nor can you reset the remote without tv power key.
What keys are not working on the old remote, you can take each remote apart, cut the rubber membrane to frankenstein a working remote? But not cut a single key by itself, it has to be at least two together, more keys are better. A single key will could be pulled out of the remote too easily.