I'm still surprised at how often a non-working game is a very easy fix.
When you say non working what exactly is going on? No power at all, including monitor, marquee light?
Check main power cord and all connections.
Replace fuses.
Make sure safety switches are pulled out.
With the back door missing, that Tron might be just that.
Monitor on but no boot?
MCR, new interconnect cables, possibly new filter caps on the power supply.
Plays blind?
Monitor rebuild.
A working game will always have more selling/trading power that a few steps can help with.
That being said - these were two great pick ups. My suggestion would be to find an arcade/barcade that still has a Tron/Vs. and give them a play or two. Trons are sought after and it is highly doubtful another free one will come your way.