Help! Setting up a PXE server on my Ubuntu laptop...

Hello all! Been tearing out my hair over this for a while at work.

We received a Google SEA that had it's setup password enabled, rendering it a pretty heavy paperweight, and after doing some reading in other subreddits, it seemed like the best course of action was to try and flash a new BIOS onto the server, specifically the Poweredge R730 BIOS, as that's what this SEA is a factory reproduction of.

My plan was to use a laptop I have running Ubuntu 18.04 to host a PXE server and flash the BIOS onto the server using the PXE boot option - however I cannot get the damn DHCP server to start! It's giving me an error of "no interfaces listening", even though I've designated the ethernet port as the interface. Does anyone have any experience doing what I'm attempting here? Is there an easier way to do this? Thought it'd be fun but after a few hours I'm ready for a simpler solution...