Measure voltage on PPBUS_G3H, PP3V42_G3H, PP5V_S5 and PP5V_S3 on your logic board. Red probe on point where voltage shows up, black probe on ground.

Then switch multimeter to diode mode. Red probe on ground, and black probe on the following points; measure SMBUS data line ends of R5280 & R5281 WITHOUT battery or charger plugged in, using diode Should be 0.435-0.461 on a non-&&^&@@ up board.

You will need a multimeter, schematic, and boardview for your specific logic board model number to begin this journey. If you are willing to follow along, I can help you troubleshoot the problem, learn something, and save a lot of money. If this seems like a nightmare, give up and buy a new machine.