Chosen Solution
Purchased a replacement battery from iFixit but the battery is not recognised. Have tried an SMC reset but this hasn’t remedied the situation. I attach a screen grab of the coconutBattery app running: battery has 0 charge cycles.
Your screenshot uploading failed, so please update. Would be interesting to know why you replaced your older battery, but if that one didn’t charge either, you might have a logic board issue at charging circuitry. New batteries are usually sold at about 70% capacity charge, thus it should have worked out of the box even without charging it. If you used an aftermarket charger that might be the original culprit, but such issues may happen with an original magsafe nonetheless. Hard to say it for sure without testing, but you might need a component level repair or a board replacement.
