Below are instructions on How to make a PC detect a DEAD MTK device after flashing with a wrong Stock ROM (Firmware).
It is always advisable to backup the Stock ROM (Firmware) of the device that you are about to flash, and it is never wise to flash the preloader.bin file found inside a Stock ROM (Firmware) folder except you are really sure that the preloader.bin is exactly the one for that device. But since we are humans we are bound to always make mistakes.
If you made a mistake of flashing a ROM with a preloader.bin file which is not the one of the device, the preloader partition gets corrupted thus making the device not being detected by the PC, boot or even charge ie Dead Mode. Since it cannot be detected, there is no way you can reflash the phone with the backed-up ROM or even when the original ROM of the device is now available.
This post will show you how you can get your PC to be able to recognize and detect the device again if it's in such situation. This process to repair dead boots of mtk devices is known as Test Point.
Note: Please read the "Important Notes" and the "Disclaimer " at the end of the post before taking any process.
Step 1: Unscrew the device and take out the board (panel) . On the board, search carefully, you will find various labels like Tx, Rx, Vcc, KCOLO, COLO, KOLO, GND etc which are either golden or silver in colour.
Step 2: Now, locate any golden or silver point on the board labeled "KCOLO" or "KOLO" or "COLO". Most times, these points are found at the volume terminal.
Step 3: Solder a wire on that point (KCOLO, KOLO or COLO) (jumper).
Step 4: Again, locate the or any golden or silver point with the label "GND" or a normal ground on the board. Join the wire from KCOLO or COLO or KOLO (as in Step 3) to GND on the board.
Step 5: After joining this 2 points, try flashing the device with its exact (good working & matching Stock ROM (Firmware), connect the device to the PC using a USB Cable and see if it detects as this shows MTK USB COM inside device manager.
If it doesn't, use another point with the same labels till your device gets detected by the PC.
Step 6: After a successful flashing process, cut off the wire which you had connected, couple back the device & reboot.
Disclaimer: RomShillzz is not liable for whatever that may happen to your device after using the above instructions. Every action (steps) you take is strictly at you own risk.
[*] Never use the Tx, Rx, Vcc or any other point because the carry some amount of voltage.
[*] Phones with no (KCOLO, KOLO or COLO) on its board are mostly Spreadtrum (SPD) devices which rarely dies or goes on a dead mode.
[*] This method (Test Point Method) is 100% tested by me (RomShillzz).