Modem always disconnects after phone being dropped
#1
Earlier today I accidentally dropped my PinePhone while trying to get it out of my pocket and after hitting the wooden floor there were a couple of cracks across the screen (despite the rubber case and the screen protector). I guess I would have to replace it soon anyway because of the screen delamination issue. Apart from some misbehaving keys in the bottom right corner of the keyboard (although that's not where the cracks are) the phone is functioning alright.

The only thing that doesn't work anymore, and that's a pretty major thing, is the modem. No matter how often I restart the phone or ModemManager, the modem just won't come up. I'm prompted to enter my SIM card's pin and then it vanishes. It's just like the known problem where the modem disappears sometimes, but now it's all the time. Looking at the dmesg output it shows the same symptoms: First the modem is attached and shortly after it is disconnected.

Does anyone have an idea how to troubleshoot and maybe fix this? At the moment I don't have the tools at hand to open the phone, but in a couple of days I will and then I can take a look inside too. But I don't know what the problem could be in the first place since the modem is soldered to the mainboard and those connections shouldn't be affected by a drop not that severe?

Any help saving me from buying a new phone altogether is appreciated!
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#2
(07-16-2021, 06:38 AM)kqlnut Wrote: Earlier today I accidentally dropped my PinePhone while trying to get it out of my pocket and after hitting the wooden floor there were a couple of cracks across the screen (despite the rubber case and the screen protector). I guess I would have to replace it soon anyway because of the screen delamination issue. Apart from some misbehaving keys in the bottom right corner of the keyboard (although that's not where the cracks are) the phone is functioning alright.

The only thing that doesn't work anymore, and that's a pretty major thing, is the modem. No matter how often I restart the phone or ModemManager, the modem just won't come up. I'm prompted to enter my SIM card's pin and then it vanishes. It's just like the known problem where the modem disappears sometimes, but now it's all the time. Looking at the dmesg output it shows the same symptoms: First the modem is attached and shortly after it is disconnected.

Does anyone have an idea how to troubleshoot and maybe fix this? At the moment I don't have the tools at hand to open the phone, but in a couple of days I will and then I can take a look inside too. But I don't know what the problem could be in the first place since the modem is soldered to the mainboard and those connections shouldn't be affected by a drop not that severe?

Any help saving me from buying a new phone altogether is appreciated!

You could check to see if the antenna is still connected.
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#3
cracks on the screen from wooden floor impact with rubber case ? strange

have a look at the physical switches on the back of the phone, they may have been damaged or moved to an unstable position and turn the modem on and off randomly

if the impact was indeed so strong anything can have gotten out of place or even the modem chip may has lost contact

of course if something else is short-circuited it can cause a power surge that restarts the usb hub

only if you are lucky enough you will find the problem
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#4
(07-16-2021, 07:42 AM)swiley Wrote: You could check to see if the antenna is still connected.
Will do when I'm back home where I have tools. But I figured in case of a loose antenna I might have no signal, but wouldn't lose the modem altogether.

(07-16-2021, 07:42 AM)mouffa Wrote: cracks on the screen from wooden floor impact with rubber case ? strange

have a look at the physical switches on the back of the phone, they may have been damaged or moved to an unstable position and turn the modem on and off randomly

if the impact was indeed so strong anything can have gotten out of place or even the modem chip may has lost contact

of course if something else is short-circuited it can cause a power surge that restarts the usb hub

only if you are lucky enough you will find the problem
I think the drop was pretty unfortunate, I only had one free hand and the phone did some spins on the floor more or less face down, maybe it even hit the base of a lamp, not sure. There are two clear points of impact from which the cracks start.
Thanks for the advice on the switches. They didn't move though and toggling the modem switch doesn't help. I will take a look inside the phone later, but it seems strange that apparently the modem is attached and then disconnected just like when it irregularly loses connecition the other times.
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#5
Update: Today, after having shut down the phone completely for a bit rather than just rebooting it, the modem seems to be working again. I already had a couple of disconnects, but I think still within the limits of the usual ones. I hope it stays that way.
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