My wiring is messed up on the rear hood switch or the mechanism to unlatch the hood is broken, is there any way to manually get the rear hood up ?

If the lock is messed up there is no way to open it without drilling out the lock. Sorry

does it make any noise at all? if does, remove back seat (in owners manual on how to) crawl thru to trunk, thee is pull cable for emerg. pull it and it will open. with open is easy to replace elec. lock mechanism...

you can't get into the trunk of a Fiero by crawling behind the seat. The motor is behind the seat. If the key don't work and the electrical switch don't work you have no out except to have the lock drilled out.

It sounds like this is a switch issue based on your description. If the key still works, that will just be what you have to do. If that won't work, then ya you have to drill out the lock. If it's just an electrical issue, you'll have to talk to someone who has that option or look for a wiring diagram or something to figure out the issue. My Fiero does not have the trunk switch so I have no particular experience with it.