OHMAXX/Gosund EP2 Smart Plug: New Chip Issue? Tuya-Convert Compatibility & Firmware 1.0.6

Hello,
so I recently bought a 4 pack of these smart plugs off Amazon.
They are branded OHMAXX, but on the plug they have the Gosund logo.
All of them came with firmware version 1.0.4 and were incompatible for tuya-convert.

So I did what many people did and emailed Gosund support to update the firmware to 1.0.6 and make them vulnerable for OTA flashing with tuya-convert, and they did it for all of them.

Now the problem:

Tuya-convert only works for 1 out of 4 plugs. For the others it tells me that it is not an ESP-chip.
I noticed that the one it worked on has the lowest serial number (72xx) for the last 4 digits, while the other 3 were much higher (82xx).
Did Gosund start using a different chip? Any experiences?
I also tried tuya-cloudcutter, but the chip doesn't seem to be compatible for that as well.

I don't know about this Gosund plug, but when looking to our teardowns list, I can see some Gosund devices with BK7231:
https://openbekeniot.github.io/webapp/devicesList.html
Can you just open your device and check, give us some more detailed photos?

It is also possible that's still ESP, but it has the tuya-convert vulnerability patched. I have seen such devices as well.

OpenBeken supports many devices, BK7231, BL602, W800/W801, W600/W601, XR3, so there is a fair chance we can figure out something for you.

EDIT: Does your gosund plug support Bluetooth pairing? Quick device scan? The one that shows device before selecting device type in Tuya app?
If so, the chip inside is not ESP, because quick pairing requires Bluetooth...

The plugs do not support quick pairing.
If it were a BK7231 I think tuya-cloudcutter should have worked.

I will try and disassemble it later today, but I think that won't be possible without destroying it.
As I want to be free from the cloud, the plug has no other use for me though, so it's fine.

Edit: What seems strange to me is that they came with the same firmware 1.0.4 and Gosund updated them all to 1.0.6 for me. Wouldn't that require the same chip?

I have no idea, but I know that Tuya has no standards when it comes to versioning and updating.

Btw, isn't your socket easy to disassemble?
It looks like BW-SHP6 and I did BW-SHP6 teardown some time ago:
https://www.elektroda.pl/rtvforum/topic3893014.html

I just had a look at it, the hidden screw does not exist in my version. Guess they removed it and it is glued together now.

Oh no! Are you sure? Please double check, that's bad.

Here's a more extreme teardown of similar sockets, but they were hard to handle:
https://www.elektroda.pl/rtvforum/topic3917832.html
The article above (not yet translated?) has shown a method where you can just cut off the part of plastic casing and expose programming pins.

Okay so I came around to opening it up.
Yeah the screw is gone, but I found a way to rip off the clear plastic part and disassemble it from there.

It is actually still an ESP8285. No idea why this was not compatible with tuya-convert then. Same chip and same firmware as the other one that worked. And believe me I tried it a lot, so it was not just an unlucky connection problem or something like that.

Any idea what's the difference here?

It's just the way it is. Some of products have patched vulnerability.
I had the same experience.
For example, this product:
BKL1250 E27
worked with tuya convert for me, but that one:
BKL1262 - RGBCW GU10 LED
failed to handle tuya-convert with: