In the list of partitions, make sure PRELOADER is checked. If you only want to fix the boot, you can uncheck everything except Preloader, though a full "Firmware Upgrade" is often safer. Change the flash settings to "Download Only." Hit "Download" and wait for the green checkmark. Common Issues and Fixes
Common errors included:
A user used "Format All + Download" in SP Flash Tool. This erased the Preloader, NVRAM, and IMEI. The phone was a hard brick. No boot. No LED. The MTK repair tool fixed the Preloader partition, restored NVRAM via a backup, and the phone was revived. mtk preloader repair tool fixed