here's my take on this

the first part is the colorful one, however they depict sadness. this is seen through the small rewind shots which means they want to go back and do smth right. the second part is seen as grayscale which means they are already back but are now satisfied.

"eyes wide open" means that such thoughts have been an eye-opener for them to know what they really want

"can't stop me" is their cry. no one can stop stem from wanting to get the satisfaction and happiness of correcting smth from the past.

imma update this thread if ever i have more "theory" analyses HAHAHAHAHAHAHAHA