Hi John Doe
Have you browsed the official HP troubleshooting page for your model? There is a link to it on the IFixit device page for your model. It may provide some answers. For example, this support page seems to describe the issue you are having, particularly in regards to the amber F12 light. Try following the steps at the posted link. Following these steps should recover your BIOS, and allow you to install the fix from HP (provided in the link).
I hope this resolves the issue. The community will continue to search for a solution until your problem is resolved.