Vex IQ Robot Brain Gen 1 won't turn on after prompting a reboot

[Foster]

Hey, welcome to the forum. You need to reset the brain to accept the default firmware. Searching on VEX IQ Reset would have gotten you to this post from 2016.

Vex IQ Reset

Hey Crispierry, All you need to do is boot the brain in “Update Mode” (or DFU mode). To do that, power down your brain and then power it back on while holding down both the up and down arrow buttons. This will force the brain into “Update Mode” and when you plug it into the PC with the VEXos Utility running it will recognize that it needs and update. Then just click the update button and you should be good to go. Thanks Levi

Do the hard reset step and then it should accept the firmware download via VEXOS.

Have fun with your new IQ brain!