Won’t power on, sensor light flashes three times when first plugged in

I have a 55 inch TCL roku tv, I’ve had it for three years. I went to turn it in the other day and nothing happened. I went through all your basic troubleshooting steps. Replaced the remote batteries, confirmed the infrared light worked, unplugged the tv, factory reset the tv, etc. The sensor light does not respond at all when I use the remote or push the power button on the tv. But when I unplug it and plug it back in, the light flashes three times… Does anybody know what this means? Spent two hours with a customer service rep, and they were no help. Is it fixable, or do I give up? Thanks in advance.