Bootloader error in pixhawk 2.4.8

i am using pixhawk 2.4.8, i had flashed arduplane firmware version 4.0.9 via mission planner, two weeks ago and was working fine till now, suddenly when i powered it its showing I/O bootloader error , and the main LED is not glowing, i tried reinstalling the firmware but still it is giving the same error. kindly guide me as to what should i do

Good day,
did you try keep push the safety switch during flight controller start up?
Do you mind provide more info about what version of 2.4.8 you own and the procedure you have done for flash the firmware pls

what is the error showing in mission planner or it is not connecting to mission planner ?