Can you guys help me with fixing this quest that broke from recent roblox updates?

If anyone can help me fix the scripts to this quest I'll be very great full!

Link: https://www.roblox.com/library/3789373883/Quest

I've been trying to do this project for over a month! And now I'm starting to think I can never get this right!

How it broke is the new roblox updates.

If you are willing to help me, this is how I want it, I just want it so if you read dialog from the Trainer a gui will pop up that gui is the quest, and if you accept it, the gui goes away and a new gui pops up. That gui is the achevement gui so then you have to find a key which is the achevement, and then if you get the key you can talk to the trainer again and then the reward is that you can pick up a KeyCard that opens a door that I've done already. Thx!