No Connection to Carrier from Pinephone 3G Model

[merlin]

OK I reflashed the Modem Firmware:

It was successfull
[034.898]: THE TOTAL DOWNLOAD TIME IS 29.555 s
[034.898]: Upgrade module successfully.

But the problem is still the same:
No connection to carrier!!!

Okt 23 09:55:44 alarm kernel: modem-power serial1-0: ===================================================
Okt 23 09:55:44 alarm kernel: modem-power serial1-0: Version:        RPMR07A03_1:37500: Dec  2 2019
Okt 23 09:55:44 alarm kernel: modem-power serial1-0: Version:        TZR07A03: Dec  2 2019
Okt 23 09:55:44 alarm kernel: modem-power serial1-0: Version:        SBLR07EG25G01_1:37500: May 30 2
Okt 23 09:55:44 alarm kernel: modem-power serial1-0: Build  Date: 2020-06-13,09:14
Okt 23 09:55:44 alarm kernel: modem-power serial1-0: Custom Name : STD
Okt 23 09:55:44 alarm kernel: modem-power serial1-0: Branch  Name: 9x07_R07_NEW
Okt 23 09:55:44 alarm kernel: modem-power serial1-0: Project Rev : EG25GGBR07A08M2G_01.002.07
Okt 23 09:55:44 alarm kernel: modem-power serial1-0: Project Name: EG25G
Okt 23 09:55:43 alarm kernel: modem-power serial1-0: ===================================================

I only get this:
Okt 23 09:55:52 alarm ModemManager[3780]: <warn>  [modem0] couldn't load supported assistance data types: LOC service: general failure
Okt 23 09:55:51 alarm ModemManager[3780]: <warn>  [modem0] couldn't load list of own numbers: Couldn't get MSISDN: QMI protocol error (16): 'NotProvisioned'
Okt 23 09:55:51 alarm ModemManager[3780]: <warn>  [modem0/sim0] couldn't load list of emergency numbers: uninitialized emergency numbers list
Okt 23 09:55:51 alarm ModemManager[3780]: <warn>  [modem0/sim0] couldn't load operator name: Couldn't get home network: QMI protocol error (16): 'NotProvisioned'
Okt 23 09:55:51 alarm ModemManager[3780]: <warn>  [modem0/sim0] couldn't load operator identifier: Couldn't get home network: QMI protocol error (16): 'NotProvisioned'

And if I search for the network in phosh manualy this:

Okt 23 09:57:28 alarm gnome-control-c[3945]: Error: scanning networks failed: Zeitüberschreitung wurde erreicht
Okt 23 09:57:42 alarm ModemManager[3780]: <warn>  [modem0] couldn't load operator name: Current operator description is still unknown
Okt 23 09:57:42 alarm ModemManager[3780]: <warn>  [modem0] couldn't load operator code: Current operator MCC/MNC is still unknown

From my side it's not an Error with the firmware.
Currently I tried 3 different SIM Cards,
and wrote the whole firmware to the modem.

I think the Modem is broken somehow.

This may seem simple, but have you checked the connections to the antenna and looked for anything on the circuit board that may not be right - i.e. loose/overtight screws, a spec of solder somewhere or not where it should be? Something amiss with the sim card tray? It seems the modem is functional but just isn't connecting.

I didn't open the device until now.

I tested around with AT commands (first time trying this).
I wrote a library in python to have a simple AT Commandline.
The sim is correctly connected, I could read out the  ID of the SIM:
--> AT+QCCID
<-- +QCCID: 89120000.....

Reception power is really low:
--> AT$QCSQ
<-- $QCSQ :-91,-2,0,0,-93

Tomorrow I'ill take a screwdriver and have a look at the antenna.