I bought a Sony Xperia X Performance from LYN garage sale last week. It was at Android 6.0 and once I connected it to my home Wi-Fi it started to update and went all the way to the latest Oreo 8.0. I only inserted a sim card after the update but it now doesn't detect any sim card (tried Digi & Maxis).

Contacted the seller and he told me that he checked with the guy who sold it to him and the original seller told him its a Japan DoCoMo installed with a global rom and should not be updated because it will revert to Japan rom and become sim locked.

Anyone has any suggestion on how to fix this problem? Any shops can unlock sim? Appreciate any advice. Thanks.

Rooting or maybe get in contact with sony japan

root it with an international rom

go xda

If I can root it, possible to remove the sim lock? Tried googling about this but all the posts keep saying that rooting & unlocking sim is not the same (obviously). But they don't explain how to unlock once rooted.

Don't think Sony will help because there is no warranty and its not their problem but will send them an email anyway to see how it goes.

Have been reading stuff at XDA to figure this out but I have never rooted before and its very confusing.
Any suggestion what I need to do? This is what I think I need to do but some guidance will be welcome.

Use flashtool to flash to downgrade to 6.0
Unlock bootloader
Flash to new rom

Will the above remove the simlock?

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This post has been edited by kurangak: Jan 29 2018, 04:48 PM

Any other suggestions?

None that i know of.

Just want to provide an update for the benefit of others who may encounter this problem.

I managed to fix the problem by flashing Sony's official Generic Global Rom. No rooting or unlocking bootloader are required.

You will need 2 tools:
1) Xperifirm - this tool will let you choose and download the official firmware that you need for your phone. If there is no Malaysia specific firmware, look for the global version. For the Xperia X Performance, it was called Generic Global. This tool will work for all Sony smartphones (maybe not the very old ones).

2) Flashtool - this tool helps to flash the firmware you downloaded above to your phone. There are various tutorials available on youtube. I used those videos to guide me through. You can also rely on the tutorials for other models as the process is similar. You need to update the driver for flashtool first depending on your phone model. For newer phones, you just select the first 2 drivers at the top. If your phone has the drivers listed separately, choose that and also the 2 at the top. The rest just follow the tutorial and flash to the new firmware accordingly.

I have disabled auto system update to avoid this problem recurring in the future. But I somehow doubt that the firmware installed on my phone previously was the Global Rom. Why would Global ROM update to a ROM that causes simlock?
Anyway, I'm glad that the phone works now. Thanks for those who gave pointers and opinions.

nice one TS

hi Bro,

I check the bootloader allow :no
is that mean cannot flash ?
Check the unlock sim network [] =0

Hv u check bootloader allow before u flash ?

I thought this only happen to iphone only.