Boot loop, unauthorized computer connection, need to hard reset

My Amazon Fire TV stick is in a boot loop due to an APK my brother installed on it, and this app seems to run on startup. It doesn’t respond to the remote control cause it is in a boot loop on the orange fire TV logo before it comes on. Connecting it to a computer doesn’t work because it isn’t authorized. There is no device this stick has been authorized to.

I was thinking the only option I have is to hard reset it; physically. Is there a method I can follow to reset the memory of my stick taking into consideration that there is no physical method indicated by the manufacturer?

Other suggestions?

Thanks in advance!