How can I disable Lost Mode for my MacBook Air 2019?

Over a month ago I put my macbook into lost mode because I couldn't find it after leaving it at work. When I found it I entered the pin that I set when I put it into lost mode and it unlocked and was working fine, but it would not allow me to mark the device as no longer lost on my iphone. When I went on my break my computer turned off and then would not let me back in with the same pin that I previously entered. When I went to www.icloud.com/find there was no pin being generated and it would not let me unlock it via the website. Since then I have brought my mac to two separate apple stores and communicated with multiple apple support agents over chat. At the first apple store they told me I had an activation lock on my computer and had me fill out the activation unlock form online. I was emailed back by apple and they informed me that I did not have an activation lock on my computer. The second location that I went to they told me that my only option was to factory reset my computer and that it was a software glitch, and that I could go to an outside company for data recovery, which I may add is anywhere from $2,000-$5,000. When I spoke to support agents over the chats they told me that apple support technicians at the apple stores should be able to bypass the firmware on my computer with their systems, however at both locations the technicians seemed confused by what was going on with my computer (same) and didn't really know what to do when there wasn't a pin being generated on www.icloud.com/find. Writing on this page is my last resort as I am a college student with countless files and important photos on my computer that I have not backed up, which I know I should have, but I never thought that would be put at compromise due to a apple software issue. I can not afford the data recovery for my computer. Thank you for any help offered!

[Re-Titled by Moderator]