It is only a guess on my part.
If you can watch channels but not record then there is some sort of disk access problem. What I don't know is whether before your first reset you could play back any old recordings - assuming you had any. If you could but can't record new ones then, as I said, the likelihood is the disk has gone read-only. This has only happened to me once (not sure which Humax model) and reset/reformat/power-cycle resolved the problem. Might be worth a few attempts increasing the power off time. If that doesn't work or you were unable to play old recordings then the disk is probably faulty (or maybe the connection is loose/corroded). Whether it is recoverable I don't know. Recovery probably requires removing the disk, connecting it to a computer running Linux and using various tools to examine and possibly repair the disk - or you could replace the disk. I don't have the experience of doing that, so can offer no further information.
If it isn't a disk problem - I still suspect it's gone read-only - what else would stop recordings taking place? My initial questioning was to ascertain whether attempts were being made to record from duplicate (low power/quality) channels. That appears not to be the case if the live (watchable) channel can't be recorded.
I'm at a loss to think of anything else.