Long story short, I have a long time client that used another firm for an upgrade and he's having an issue with his 55"A8G getting 6 red blinking lights on turn on, more than half the time.
Through some back and forth emails he told me they actually replaced it once (and the blinking had started immediately after initial install on the first TV). They also replaced HDMI cables. They also made some adjustments of some kinds and he felt it got "better" but still gets the 6 red blinks and it doesn't turn on half the time.
From "Googling around it seems the be the TV itself but one troubleshooting option was to turn on and one by one plug in each device, until the "problem" happens. This sounds crazy to me, but I'm checking to see if any of you have had or heard of this particular problem with any Sony's. I haven't personally sold or installed the A8 but a lot fair amount of A9's, 950's without any issues (except some extenders but it wasn't the TV).
Here's a list of products installed, though it just doesn't power up half the time. Not sure if it could be the Yamaha or even the power strip it's plugged into (per link from Ernie below).
55" A8G
Yamaha RX-A880BL (not even Avantage!)
Apple TV 4K
Sony BDP-S6700
Spectrum DVR

Any input would be great, this guy is a decent dude. I believe his new wife had something to do with not using me. I felt she thought my bid was to high and asked why they couldn't just use the apps in the TV. I tried to explain they have an AVR and it would be a pain in the ass and they'd hate me.
Man , I do miss the service calls. He'd give me a Cuban cigar and a bottle of wine.....