1 Permanent blue screen on startup
I have a Samsung QN82Q70RAFXZA. It was left on all night and when I woke up, it would only start for 2-3 seconds then cut off. I could hear volume in background but never had time to see the actual screen since it turned off. I took it off the wall, took off the back and diagnosed. I checked the backlights by unplugging the power board and they worked but from then on I only got a blue screen when turning on. I replaced the mainboard but no change. I have unplugged the two ribbons to the lower panels (not sure what they are called) to see if I might use the tape method to fix but no change. I am wondering if the driver board needs replacing? Any help is appreciated. oldturkey03...thoughts?
Update (03/12/24)
Sorry for the delay. I get no Samsung logo or anything else when I turn on. Note this TV is in garage and only has power cord so no other source inputs using cable or HDMI. I unplugged power, then unplugged the cable between mainboard and PB (at the PB terminal), then plugged power and that is the pic I uploaded. I circled two of the holes showing backlight is lit. The other two pics aren't great but you should get the idea of what the blue screen looks like. I assume that is simply the backlight showing through but nothing more?
Update (03/14/24)
Here is pic and I read the pins on the right side
Atualizar (03/17/24)
I am not sure if I did this correctly but here are two pics. Both from the third row which is POwer On. Bottom is the 4.55 and top is the 13.
Atualizar (03/17/24)
crwdns2934109:0crwdne2934109:0
1 
@atrsell it just shows you a blue screen? No Samsung writing, no splash screen just blue all over? Explain once more how you checked the backlight. You disconnected the power line from the power board. Then disconnect the main board from the power supply. then plug the power cord into the powerboard. Your backlights should now come on. Is that how you did it? Can you post some pictures of what the back of your TV looks like (without the back cover of course :-) and which cables you disconnected. Did you disconnect both at the same time or one at a time? Adding images to an existing question
crwdns2934271:0crwdnd2934271:0 oldturkey03 crwdne2934271:0
@atrsell you are absolutely right. That is just the backlight. Let's disconnect one of the ribbon cables. disconnect the power, dc the cable and then reconnect the power and turn your TV on. What do you get? Now turn the TV off, unplug the power, reconnect the Ribbon cable and disconnect the other one. Reconnect the power and turn it on. What do you get?
This could be the panel
crwdns2934271:0crwdnd2934271:0 oldturkey03 crwdne2934271:0
OK. I can do in about an hour. The ribbons....you mean the two that are at the bottom , correct? I have done that before and get no change but will try it the way you mentioned and get back to you asap
crwdns2934271:0crwdnd2934271:0 @rsell crwdne2934271:0
and what do you mean about "disconnect the cable"...
crwdns2934271:0crwdnd2934271:0 @rsell crwdne2934271:0
I decided to quickly do it. I also know what the cable is (ribbon). I did both cables and there was no change
crwdns2934271:0crwdnd2934271:0 @rsell crwdne2934271:0
crwdns2934275:012crwdne2934275:0