Can I use a hot glue to cover a PCB board to insulate it and prevent it from damage?

Not recommend. There are two proper methods to coat a PCB.

1. The first is via a conformal coating.
2. The other is potting epoxy.

• Depending on your electronics casework, you may be able to fill with with non-conductive epoxy.
• You have to be concerned about any cabling.
• Once potted, your gear is unrepairable. You have to watch out for connectors.
• If they will with epoxy, they won’t work any longer.
• If the PCB is depending on cooling via the case, you can try heat-conducting, electrically insulating potting epoxy.

#PCB Manufacturing

https://www.youtu.be/vr34HkBPAcw?si=d-xOTm1ZQ8F5F3fb