My Mac Pro 2009 (4,1>5,1) running 10.14.6 Mojave when dark on me last week 😢. It was a good long run. The machine turned on with no video output and SSD drive fine but didn't boot. GPU LED was flashing. After reading through a lot of the troubleshooting steps I gave up and had my brother ship his identical Mac Pro to me in Los Angeles from Oakland. He upgraded to a MBP last year and was meaning to sell his Mac Pro anyways.
CA shipping tip: Golden State Overnite shipping was only $40 versus UPS wanted $230! Saved me 11 hours of driving and $150 in gas.