[Android Q&A, Help & Troubleshooting] zeromemory_wtf:
UPDATE: I was able to debrick the phone. Read my later post for details.

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Hi All,

Thank you all for having amazing community of hackers and developers here. You guys rock.

I started my search for a new rugged rootable phone recently and I settled on Poptel P60. It is a great phone though slightly bigger than what I normally get. Nontheless, the specs are excellent and the price is fair!

I've had a limited success rooting and customizing this phone. The OEM interface is almost bearable but overall the "Customized UI" felt like a downgrade from stock Oreo. It has a very annoying feature of reverting to stock launcher on startup, even when I selected Nova as my default one. The stock launcher is not that great. This, and the lack of ability to use x.flux, Titanium Backup and other root-only apps drove me to try hacking things again.

After emailing the manufacturer they provided the firmware but it is in CPB format. I tried at least 3 different converters for CPB to MTK Scatter and they all either freeze or hang. No luck.

Instead I did a rom readback with SPFlashTool and then cut up the partitions with Wwr. Now I've finally had the recovery partition! I used CarlivImageKitchen to port TWRP from a similar device, Ulefone Armor 5. The chipset and resolution are same. After some trial and error it worked! I had to use USB-OTG for input and external sd card had a weird label, but I was able to install Magisk from the SD card to root, followed by XPosed, full package. It worked! If anyone needs my ported TWRP Recovery for Poptel P60 just ask!

However, the manufacturer UI did complain a lot about the phone being rooted. Eventually, somehow, Magisk stop receiving root requests. They never showed up and timed out! Very strange, because apps that already received root continued working. I tried a lot but could not fix the issue. I was fed up. I wanted to do a manufacturer reset (in hopes of starting from scratch and then attempting to port Lineage or something) but, as I've mentioned, I have not received a firmware compatible with SPFlashTool. I tried to make one from Armor 5. The partitions were almost the same (both are MT6763 devices). One was out of order, and offsets were different and I patched all those. To be clear, I used all the partitions and layout extracted from my rom readback that was cut up by Wwr. I only used the Armor 5 scatter as a reference for file format. I edited the layout to match everythign I saw in Wwr.

This is where the horror begins. I tried flashing (Download Only) with SPFlashTool but got some error saying something changed. "Do you want to do Format & Download instead?". Being an inexperienced idiot that I am, I said yes!

Now, the phone appears bricked. No lights. No screen output. Cannot enter fastboot. Cannot enter recovery. Cannot boot.

I have a feeling the preloader got corrupted. I'm not sure this is the case because I've omitted the preloder from download. At least the first time the phone started acting bricked. The device still shows as Mediatek USB VCOM device and flashing gets initiated but all attempts to flash result in errors. MA checksum mistmatch or something along that order. I've tried a lot of things and I'm stuck! For good or for worse I've tried flashing Ulefone Armor 5 preloader but I'm getting the same error when trying to flash it.

Here is what I have...

- Stock firmware in SPB format. I can't use it and nothing I tried worked for converting it.

- ROM dump made with SPFlashTool

- Wwr was able to extract every partition except preloader. This includes nvram, etc. I'm not sure why it was not able to extract the bootloader.

- TWRP port that worked. Seems not useful if the phone does not start.

- Preloader for Ulefone Armor 5, (same chipset and resolution)

Clearly I am an idiot for using "Format & Download" option. I've found posts later suggesting against it. I am also over my head for trying to tackle a new device by myself, though I have had a marginal success with porting TWRP and installing Magisk.

Now, I feel like idiot and I am stuck! I beg you, XDA developers, if you have any advice (besides not being an idiot in the future), please share!