I've still not been able to get my lock code working since the V21 update, so I thought I'd take my phone into my local Nokia Care Centre to see if they could fix it.
The phone's under warranty after all, and it's a firmware update via the NSU program that's broken it.
I was flabbergasted when the sales rep (it was a Carphone Warehouse) said it'd cost �10 to reflash the phone, despite me insisting it was a warranty issue.
I said I'd already tried a factory reset and reinstalling the firmware, but he said they'd do a 'deeper' reflash.
Not impressed. 😡
Protip:
1. Go to Change Lock Code screen
2. Hold down the # key until input changes from Abc to 123
3. Enter your old lock code
4. Watch in amazement as your realise what you kept doing wrong
When I go to change my lock code it's already in 123 mode when I access the screen. Entering the code in abc mode doesn't work either.
Are you sure it was during the update to v21. I've heard this happening during the update to v20. It was a major issue with that FW. However, the changelog for v21 specifically addressed this issue. It was majorly this issue, aside from others of course, that made Nokia roll out v21 just a couple of weeks after rolling out v20.
In any case, you have to insist that Nokiacare do it for you for free. If you do find a hard time having them do that for you, you have an alternative - the vulcan death grip.
Press the green, red, and camera buttons as you power the phone up making sure all keys are pressed all at the same time until the prompt for your country appears. This will hard reset your phone. This method works only for FW v20 and v21.
This will however erase everything on your phone memory and UDP will not work.
Hope this has helped you sort out your problem.
Thanks for your help. I've already tried the vulcan death grip, with no success.
So looks like the only recourse is to get it re-flashed at a care centre. I might try a different care centre instead and see if I get better service.