A tablet battery which wasn’t charging. Having tried the usual ‘tricks’ to recalibrate the battery charging monitor I decided that yes the battery had physically become damaged, it was time for a replacement.
The new battery was £7.50 but it took about a week to arrive (the tablet owner was in no hurry). For situations where a quicker turnaround is needed you can source batteries from UK suppliers but there will be an increased price.
(I always ask which is preferred when replacement parts are needed for a job, i.e. is cost or speed more important?)

Total charge £15