In reply to a post by stniuk:

I would back up, erase and reinstall as advised.

I did that and at first I thought it had worked but I was wrong. My final contact with Apple Support, they wanted me to post it in to have a technician repair it.

I've now got an iPhone 11 and I'm very pleased with it. The old phone is on Gumtree!

p.s. - I realise that I'm very much in the minority but I'm by no means the only person who has had the problem.

Edited by longedge (Sat 12-Dec-20 12:59:25)

It could be the battery is failing. Check battery Health settings > battery> battery Heath. I had mine replaced over a year ago under the discounted battery replacement program. Just out of interest have you ever replaced the battery?

No it hasn't been replaced but it has 91% life left and an online remote diagnostic with Apple support indicated that the battery itself was not the problem.

Anyway it's done now. I use the phone more for listening to audiobooks and radio than making calls and the sound quality is far superior to my old phone so I'm happy to have the new one - an early Christmas present from me to me

I also got a Qi charger and I love that as well.

Ah .... I’d imagined from earlier posts that your experience had turned you to ‘the dark side’ for your replacement phone.

My child's iPhone SE (old version) started with the phantom battery drain last week when updated to 14.2. Youtube kids showing 60% use in just 3 minutes as reported by the "Battery" menu within Settings).

This was fixed by full reset, and not restoring from backup.

FYI - This iphone SE only ever has Youtube Kids on, no other apps (not even most of apple ones) and yet the battery drain bug still present.