Repair or replace? Gun safe dilemma

I ordinarily open my gun safe* with the electronic combination buttons. Recently I had occasion to try to open it with the manual keys, and discovered to my dismay that they no longer work. The lock has not been subjected to anything that might damage it; I am at a loss to understand why the keys don’t work- why the f*** did it do this? (The lock is the type that uses a cylindrical key similar to a u-bolt bike lock.) This is worrisome because opening it manually is the backup for if the battery-powered combination buttons ever lose power. Having an unopenable safe with my gun locked inside doesn’t bear thinking about.

So, what to do? I need to either get the lock fixed, or toss the safe and get a new one. The problem is that by intent I mounted my safe in such as a way that getting it loose would be a lengthy and laborious process. Any chance there’s something simple and easy to fix that could be done to the lock in place? If it has to be serviced or replaced by a professional, can that be done for less than what I payed for the safe (around $100.00)? The manufacturer has apparently gone out of business in the three years since I bought it; at least the address and phone number that came with the safe are no good anymore, and no hits on the internet.

*I dunno if you would call it a safe or more of a large lock box.

Replace.

After my OP, I was inspired to take a closer look at the lock mechanism, and with the help of a hand mirror discovered that it actually was user serviceable without dismounting the whole thing… The reason the key lock had stopped working was that the lock itself turned out to be ok, but a hex nut linking the lock to the latch mechanism had worked loose after umpty cycles of the lock. Long story short, I’ve got it in one piece again but the latch mechanism and manual lock are shoddy pieces of crap, and the whole thing will get replaced as soon as I can afford a quality safe.

OP self-answered. If no further comments or discussion, ok for mods to close.