Modem attachment refusal

[kjm]

We're running what we think are the latest gpy/modem firmwares

>>> import sqnsupgrade; sqnsupgrade.info()
<<< Welcome to the SQN3330 firmware updater [1.2.6] >>>
>>> GPy with firmware version 1.20.2.r4
Your modem is in application mode. Here is the current version:
UE5.2.0.3
LR5.2.1.0-48829

This printout is always followed by a core dump which doesn't inspire much confidence in the latest firmwares but that's another matter.

The modem won't attach

>>> from network import LTE
>>> lte=LTE()
>>> lte.attach()
>>> lte.isattached()
False

https://docs.pycom.io/tutorials/networks/lte/ says this is because the cereg might be wrong (latest formware needs cereg=1), so we checked

>>> lte.send_at_cmd('AT+CEREG?')
'\r\n+CEREG: 1,0\r\n\r\nOK\r\n'

This modem was working fine till we tried lte.attach(band=28), which is the catM1 band in AU, to try to speed up first time attachments (suggested at https://docs.pycom.io/tutorials/networks/lte/). It hasn't attached since!

We tried to backup out of the hole of yet another failed modem

>>> lte.factory_reset(debug=1)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: function doesn't take keyword arguments
>>> lte.factory_reset()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
OSError: the requested operation failed

We tried reloading the 48829 firmware into the modem, still won't attach. Any one think of something else we might try to get attachment working again?

[goldfishalpha]

Finding all these (old?) gems trying to solve my own issues.

Did you fix this? If so, what worked.

Anyone in a similar situation, I would suggest going back to an old firmware (for me 1.20.1 recovered my device), then see how far up the firmware chain you can get.
Having said that, I still don't know if my code will run now, but all the preliminary REPL tests are promising...