With [FF] it's possible to boot even semi-dead devices with damaged hardware.
Original factory DA/FDL CAN NOT DO THIS!
If you can boot device with [FF] but factory DA/FDL fails it means hardware (flash chip) may be damaged and must be replaced!
[FF] is very powerful but slow, if you need fast flashing use Boot [Factory] mode.
EMMC health status: Once you boot in [FF] mode you will see deep info about EMMC flash chip health
RAM health status: If you can not boot device with factory loaders but [FF] can works well it may says that RAM is Faulty
At first check EMMC date.
Check EOL state: If value below is not like that - EMMC flash chip may have problem.EMMC CID: F40122426977696E201000..... crc Ok
Vendor: Biwin OEM: 0x0122 ID: 426977696E20 [Biwin ] PRV: 0x10 Serial: .... 0x0003D4ED
MM/YY: 11/2020
BOOT1: 0x00400000 4,00 Mb
BOOT2: 0x00400000 4,00 Mb
RPMB: 0x00400000 4,00 Mb
USER: 0x748000000 29,13 Gb
Check EOL state: If value below is not like 0%-10% - EMMC flash chip may have problem.EOL: Status: Normal: Less than 80% reserved blocks used
EOL_A: SLC status: 0% - 10% used
EOL_B: MLC status: 30% - 40% used