Please help! 12 volt Pool light issue

[musicfan266]

Thank you to all who take the time to look at this thread, and even more thanks to the ones who comment. Here is the back information about the pool and my situation.

We have recently replaced the pool liner. The light was working before we replaced the liner. After replacing the liner, and getting everything back to together we re-installed the light. I replace the bulb, with a 12v 100w bulb (same as what came out). We wired it back up and turned it on. The light worked for a few minutes, but stopped after that. This is what I did to test it.

--- Checked the wiring at the junction box, just outside the pool enclosure.
--- Removed the light to check for water in it, and was completely dry.
--- Looked at the bulbs filament and it looks brand new. (I know looks can be deceiving)
--- The breaker is not tripped.
--- Check the GFI. I have power at the plugs, but when the test button, the reset button does not pop out. Also the reset button will not stay pressed in.

My guess is the GFI is bad but not sure. I would like to here what you all think before spending even more money, especially if that is not the issue. I have already spent $2,000 in the last week on the liner, gaskets, bulb, and chemicals. I would like to not buy items that are not broken. Thanks again for taking the time to help!!