The board level components (memory, CPU, etc) are not individually replaceable as the boards are designed by Google, not the OEMs.
This all assumes that you are not paying for repair labor, however. For very inexpensive Chromebooks, The repair technician's time may cost more than a whole new device.
Disclosure: Chrome OS engineer, but my positive opinions about Lenovo devices are my own.
Sort of like how many people who ended up in the corporate IT support/management field started out working as computer lab support techs in college, or before that, kids who worked in the high school auto shop (remember when those existed?) sometimes ended with good careers in auto manufacturing.
I always read about employers who have a hard time finding good technicians.