Q: No Service - iPad2, started with iOS 8 upgrade

Hello there, Kerappo.

Great job on the steps you've done to troubleshoot your issue. The following Knowledge Base article offers up some additional steps and recommnedations for troubleshooting cellular connectivity with your iPad:

Get help with the cellular data connection on your iPad (Wi-Fi + Cellular Model)

http://support.apple.com/kb/TS4249

Resolution

1. Tap Settings and make sure that Cellular Data is turned on. Turn Cellular Data off, then back on again.
2. Swipe up from the bottom of the screen to open the Control Center. Tap the airplane icon to turn airplane mode on. Wait three seconds, then turn it off.
3. Restart your iPad.
4. Check for a carrier settings update.
5. Update your iPad with the latest version of iOS.
6. Remove the SIM card, then insert it again. 
7. If your SIM card uses a SIM PIN, tap Settings > Cellular Data and turn SIM PIN off.
8. Tap Settings > General > Reset > Reset Network Settings.
9. If you have another SIM card with a valid cellular data account, remove the SIM card from your iPad and insert the other SIM card. If the cellular data connection works with the other SIM card, contact your carrier to report the issue.
10. Try another location. If the cellular data connection works in another area but not in the first location you tried, contact your carrier to report the issue.
11. Restore your iPad as new.

If you still can't connect to or use a cellular data network, contact your carrier, make a reservation at a Genius Bar, or contact AppleCare for more help. 

Thanks for reaching out to Apple Support Communities.

Cheers,

Pedro.