Reboot after fresh install will not work with external CD/DVD drive

I'm installing Mint 20.1 on a mini PC that has USB inputs, but no internal CD/DVD drive. I have connected an external CD/DVD drive to one of the mini PC USB ports. The installation goes according to usual plan until the message at the end of the install prompts me to restart the PC. I click on the restart message, but nothing happens (the CD is not ejected, and the PC does not reboot). I press the power button on the mini PC, holding it in until the system shuts down, then I press the power button again to boot into Mint. Is this OK to do, or will it corrupt the Mint installation? Once I power up again and get into Mint, the system seems to be responding normally, but it's difficult to tell when I don't have the alternative.