Arduino GIGA R1 boot problem

I have been using arduino giga to build a project to control a single stepper motor with some limit switches, potentiometers & toggle switches. the whole project works as intended except a weird problem - it doesn't boot after the night. no boot error [red LED] or so. it just remains blank. reseting doesn't work either.

it runs fine once i flash [using arduino IDE] the M7 core again.

Is something wrong with the board [like RAM or some chip] & replacing the board would solve the issue? or could be something else?

thanks in advance.