Replaced battery w/ ifixit kit, worked for around a year, now vanished

Hi everyone,

Thanks for reading. As title describes, I replaced an unhealthy original battery with the Ifixit replacement battery kit. All went well and I have been happy for a year. Recently I realised my laptop would instantly 'die' if the power supply was disconnected. I've tried various SMC and PRAM reset processes, plus a troubleshooting process involving disconnecting battery, resetting PRAM several times and reconnecting, to no avail.

Coconutbattery shows this...

Anybody have any ideas what else I can try to get my battery working once more?

Thanks in advance!

jason