Multiple E-Series Modules only breathing white

Hello,
i have 21 E-Series E314 Modules, where the RGB LED is only breathing white after startup. All modules have the tinker software installed and are running on Firmware 2.3.0.
The documentation says, that this color code means "Cellular off".
Since the tinker software is installed, i was expecting a green flashing LED.
After about 1 minute the LED changes into blue flashing.

I also installed the cloud debug tool, and this is what i get on all modules.

Connected to USB serial
e[999;999He[6n> 6.974 AT send 4 "AT\r\n"
0000010001 [app] INFO: Platform: Electron/E Series
0000010001 [app] INFO: Binary compiled for: 2.3.0
0000010002 [app] INFO: Troubleshooting firmware version 12
0000010002 [app] INFO: System version: 2.3.0
0000010003 [app] INFO: Device ID: 280023001747373530383332
0000010003 [app] INFO: Connecting to the cloud
10.285 AT send 4 "AT\r\n"
13.596 AT send 4 "AT\r\n"
16.907 AT send 4 "AT\r\n"
20.218 AT send 4 "AT\r\n"
23.529 AT send 4 "AT\r\n"
26.840 AT send 4 "AT\r\n"
30.151 AT send 4 "AT\r\n"
[ Modem reset ]
43.462 AT send 4 "AT\r\n"
46.773 AT send 4 "AT\r\n"
50.084 AT send 4 "AT\r\n"
53.395 AT send 4 "AT\r\n"
[ No Reply from Modem ]

76.448 AT send       6 "ATE0\r\n"

[ Modem::powerOn ] = = = = = = = = = = = = = =
86.759 AT send 4 "AT\r\n"
90.070 AT send 4 "AT\r\n"
93.381 AT send 4 "AT\r\n"
96.692 AT send 4 "AT\r\n"
100.003 AT send 4 "AT\r\n"
103.314 AT send 4 "AT\r\n"
106.625 AT send 4 "AT\r\n"
109.936 AT send 4 "AT\r\n"
113.247 AT send 4 "AT\r\n"
116.558 AT send 4 "AT\r\n"
[ Modem reset ]
129.869 AT send 4 "AT\r\n"
133.180 AT send 4 "AT\r\n"
136.491 AT send 4 "AT\r\n"
139.802 AT send 4 "AT\r\n"
143.113 AT send 4 "AT\r\n"
146.424 AT send 4 "AT\r\n"
149.735 AT send 4 "AT\r\n"
153.046 AT send 4 "AT\r\n"
156.357 AT send 4 "AT\r\n"
159.668 AT send 4 "AT\r\n"
[ No Reply from Modem ]

162.870 AT send 6 "ATE0\r\n"
0000172871 [system] INFO: Retrying SIM check

[ Modem::powerOn ] = = = = = = = = = = = = = =
173.181 AT send 4 "AT\r\n"
176.492 AT send 4 "AT\r\n"
179.803 AT send 4 "AT\r\n"
183.114 AT send 4 "AT\r\n"
186.425 AT send 4 "AT\r\n"
189.736 AT send 4 "AT\r\n"
193.047 AT send 4 "AT\r\n"
196.358 AT send 4 "AT\r\n"
199.669 AT send 4 "AT\r\n"
202.980 AT send 4 "AT\r\n"
[ Modem reset ]
216.291 AT send 4 "AT\r\n"
219.602 AT send 4 "AT\r\n"
222.913 AT send 4 "AT\r\n"
226.224 AT send 4 "AT\r\n"
229.535 AT send 4 "AT\r\n"
232.846 AT send 4 "AT\r\n"
236.157 AT send 4 "AT\r\n"
239.468 AT send 4 "AT\r\n"
242.779 AT send 4 "AT\r\n"
246.090 AT send 4 "AT\r\n"
[ No Reply from Modem ]

249.292 AT send 6 "ATE0\r\n"
0000259293 [system] INFO: SIM/modem not responsive or SIM not inserted/requires a PIN.

After this last message the Module starts flashing blue

Do we have a hardware issue here or what can i do about it

That log would typically indicate a problem communicating with the cellular modem. It could be a hardware issue, a power issue, or baud rate issue (this only happens with certain combinations of upgrades and downgrades of Device OS).

How are you powering the E-Series module?

Your log included a Device ID so I looked it up and it was manufactured on 2019-05-21 and at that time, the MCU was able to power on the cellular modem and read the ICCID and IMEI.

It is powered via a 5V /2A Voltage regulator on the external board, where the e-Series module is soldered to.
I also tried to power it over the USB Connector with a external USB Power Supply 5V/2.5A.

We are using this PCB in serveral hundrets of our products with no change in the last years and had no issues with the E-Series Modules until this problem.
We have produced a batch of 50 units with 27 Pieces E310- and 23 Pieces E314 modules. All of the E314 Modules out of this batch have this same problem.
But we also have other Modules with E314, that are working fine.

DFU Mode is working and i can flash user code and firmware but i can´t bring the module into listening mode by pressing the mode button.

If I flash our user program, it works normally. It just wont connect and keeps breathing white and after a while blue.
Flashing the tinker code doesn´t change anything.

What else could it be?