Why both lights blinking

That's the WIC error on these LED panel Epsons, but the error codes are vague on these, use this to see what you have:

If you have the paper/ink light, that is historically waste ink. You will need to replace the waste pad or bypass it with a external box and reset it on these models with a tool like WIC reset tool. Sometimes it's the borderless pad on the printing path as well but those will print normally in bordered mode, the main pad shuts the printer down. That's the key improvement in recent Epsons from the last 5-7 years: They let you print with a full borderless pad in bordered mode, the old ones disabled it if that was full even if the lower pad had 90% left.

You need the Epson part numbers 1749772 or 1830528 to get the right pad. You remove the side panel with one screw, then the box comes right out after removing 2 screws - same procedure as the serviceable pad printers but with a non resettable counter unless you clear the NVRAM.

SM here: Epson L3150 SM