Ok, thanks. And you have a new panel, so we'll eliminate that.
We're left with a couple options here. Most likely is the power supply, or maybe the main board.
Did you pay for the panel?
The L07 is a suitable sub for the L05, you're fine there. I hope you got it for around $200 after the core refund.
If you have the ability to troubleshoot with a multimeter, you can check the voltages coming from the power supply... they'll be labeled. Use the panel for ground. Make sure to do a good visual... burnt or open components, bulging/swollen or leaky capacitors. Else, replace the power supply. Well first, give me the part number from the board so I can look up pricing. Then we'll make a cost decision.