Oneplus 6 (8gb/128gb) SIM & Wifi disappears & phone reboots randomly frequently. What to do?

Question

Oneplus 6 (8gb/128gb) worked perfectly fine from July 2018 to Nov 2022. Now, problems start appearing. There are 2 separate problems - SIM & Wifi disappear & Phone reboot at random frequency. I am not sure whether the problems are linked or not.

Important point -

• Using original DASH charger since day 1, running original Battery (battery health also OK).
• As the problem worsens, time between restarts reduces from 30-40 minutes to 2-3 minutes & sometimes few seconds (sometimes it restarts at Oneplus logo loading screen).
• Phone feels slighlty heated up to the left of Fingerprint sensor

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Kindly note -

I have tried all the troubleshooting steps-network reset, factory reset, OS downgrade etc

Nearby repair shop (DOUBTFUL) - Network IC reset, Motherboard repair etc.

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DETAILED SCENARIO

In Nov 2022, Phone started randomly losing network - SIMs as well as WiFi - I changed SIM cards it started working correctly. Now after few days, the problem reappeared & frequency increased.

In Dec 2022, Phone started restarting abruptly during normal usage. It is generally coupled with NETWORK LOSS as well.

Now, I performed regular troubleshooting steps as mentioned above to no avail. Then gave phone to a trusted nearby repair shop to only temporary relief. Total 3 visits to repair shop -

1st Visit - He told that Network IC issue was there. New NW IC ₹ 2000/-

Result-Worked absolutely correctly for few hours. HAPPY!!! Then same cycle of Network Loss & Random restart & then working fine randomly & then problem again.

2nd Visit - Told that seems like 'Motherboard' problem. Repair/Refurbished MB ₹ 2500/- more

Result-Worked absolutely correctly for 48-72 hours. Elated & HAPPY!!! Flashed Lineage OS & thought everything is normal now. And demon came back again - the same cycle of Network Loss & Random restart & then working fine randomly & then problem again.

3rd Visit (April 2023)- Told that there might be some pending issue, I will check thoroughly again for 3 days & use. NO CHARGES.

Result-Got phone back after 15 days, worked fine on WiFi till it got discharged to 8-9% & I put it on charge using DASH Charger. The same cycle has again started.

I am clueless

When the phone works, it works like a charm - but suddenly, network loss & phone restart keeps happening.

Please help Stackexchange community.

Answer 1

Disclaimer: Although this may be an answer to the question "what's gone wrong?" I'll try to offer suggestions for fixes, but they may be difficult.

Based on the heat you're experiencing next to the fingerprint readerwould seem to indicate the PMIC (power management integrated circuit, see Step 8 on the iFixit guide, yellow outline) chip on that side of the motherboard. I was unable to find any wiring diagrams, but it appears from your description that they're interacting with the radio modules, which fail before the device turns off due to a power issue.

While this would take sitting down with a multimeter and circuit diagram to confirm, I think it's fairly safe to say this is a hardware issue.

Potential path to a solution: There have been some communities who have tried to enable ways of PMIC Calibration in Xiaomi Poco phones, but none that I've found doing so for the OnePlus 6.

Potential temporary solution: The only software advice at this moment would be to remain on your stock operating system if that seemed more stable, as custom ROMs have the potential to cause components to operate out of their usual bounds, but this is unlikely to be a full solution if it is truly a hardware issue.

Final solution: if it is such a hardware issue, seeking replacement of this component (or related ones, but there are a lot of power management chips on this board) would be the next step. This could, cost-wise, end up being more expensive to find and fix than getting a new phone, unfortunately.