Check and remove write protection on Mifare NTAG216?

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I have a Mifare UltraLight NTAG216 (NFC Forum Type 2).

It is not password protected, but the Android app NXP TagInfo says:

NFC data set access: Read-Only

NDEF access: Read-Only

E1 10 6D 0F

Looking at the memory dump from NXP TagInfo:

[E2] . 00 00 00 BD (LOCK2-LOCK4, CHK)

[E3] . 04 00 00 FF (CFG, MIRROR, AUTH0)

HOWEVER, the NXP TagWriter app allows me to format the tag, which successfully removed all data (I verified before and after). I can also repeat the formatting (both Erase, Quick Format, and Format all).

But any write attempts fail with a "read only" message.

How can I determine if this write protection is permanent, and if not, remove it?

According to a related question, it might have to do with the configuration pages, which can be both temporarily and permanently protected. But I'm not sure what that means.

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Magnus Timmerby On

SOLVED: After restarting my android device and formatting the tag once again, I could again successfully write to the tag.

Curiously, it still reports Read-Only as described below. I guess that's normal (perhaps for this particular chip) and it was just an intermittent problem.