Help reviving a Nexus 7 2013 Flo 32G

[drjboulder]

I need help reviving a Nexus 7 2013 Flo 32G.
This tablet has sat forgotten and dead for a couple of years. I am trying to bring it back to life. It has been several years since I have done any rooting and flashing on Android, so I am looking for a little guidance. I honestly do not recall what has left the device in its current state. But, basically it has no OS installed. The boot-loader version is FLO-04.04. I can get into recovery. The installed recovery is TWRP v2.8.6.0. I do not possess any Windows machines. I have Android Debug Bridge version 1.0.39 installed on Ubuntu 16.04.3 LTS. MTP is enabled.
But that is it. I am not able to locate the device through ADB using ‘adb devices’. As I say it has been several years since I have rooted around Android or used ADB. I did not use Linux the last time I was doing things like this. So, I am stuck as to how to proceed. I was hoping it was going to be a pretty straightforward process of picking a ROM and GAPS and flashing.
Of course not even being able to ABD into the device leads me to believe that, while not in over my head, I made need some help going forward.
Anyone care to volunteer some first steps?
TIA

 

[GSDer]

Step 1 - get access to a Windows machine. I'm guessing that most people who can help you are familiar with the quirks of Windows, and don't speak Ubuntu. I'm not even sure if a VM of Windows running on Ubuntu would be adequate. Sorry.