I would start by resetting the NVRAM.
Reset your NVRAM
To reset the NVRAM you'll need to follow these steps:
Fully shut down your Mac
Press the power button and then press the commandoptionpr keys. You have to make sure you press these keys before the gray screen appears or it won’t work.
Hold those keys down for about 20 seconds (or until you know for sure your Mac has rebooted a second time)
Let go of the keys and let your Mac reboot normally.