This took a bit of gentle prying with the plastic opening tool and the plectrum thing. I was super careful as the battery had ballooned and could have been unstable. I didn't want to damage it and have a lithium battery fire on my dining table!

The iFixIt prying tool was too clunky. The iFixIt needle nose tweezers were a much better option.

It's a bit fiddly around the camera lens end, but gently lift the frame up and it unhooks.

Not screw related: Mark the top of the cover with a felt pen or sharpie before removal. I didn’t and on reassembly, spent a few minutes trying to work out which way it went back on - Doh!

This was the time consuming part. I’d recommend having a thin bladed knife or similar to get things going. I used the small blade on my Swiss Army knife, but be careful. When it goes, it can be unexpectedly sudden. I also used a strong rubber band to stop any excessive opening of the screen.

I popped my iPhone under a desk lamp with a 60w filament light bulb in it, switched it on, (See this photo) then read the iFixIt instructions and comments. By the time I’d done that, the glue had softened enough to start work. I managed to do the whole process, slowly and methodically, without incident. The iPhone even worked after I’d put it all back together. So we’ll done iFixIt. Another satisfied customer!

The pick in my iFixIt kit was packed with the battery, not with the rest of the toolkit.

I successfully replaced the old battery yesterday. The iPhone is still working properly more than 24 hours later. It has a new lease of life. Thank you for the clear destructions, they worked a treat, along with the comments made by others.

Reinstallation: Getting the Touch ID cable and metal shield both clipped back into place was a real PITA. The best advice I can give is to take it slowly and with lashings of patience. The first effort was no good. The shield and plug weren't properly home. The second effort was better - everything works now. Hurrah!

Thole whole job took 2h 45m. It's my first iPhone battery replacement.

Next job is my iPhone 7....

My camera sometimes has this problem. When this happens, it is very annoying. I do not know why it happens, but it does. Then the problem goes away, but will come back, at a later date, for no apparent reason!