Did you try plugging it in initially after you disassembled it and reassembled it? I’ve found on chromebooks that the embedded controller doesn’t seem to wake up until the charger is plugged in after unplugging the battery. Could it be that you initially didn’t plug it in before trying it months ago, but months later you figured the battery would be low after all that time so you plugged it in finally starting the embedded controller?
Did you try plugging it in initially after you disassembled it and reassembled it? I’ve found on chromebooks that the embedded controller doesn’t seem to wake up until the charger is plugged in after unplugging the battery. Could it be that you initially didn’t plug it in before trying it months ago, but months later you figured the battery would be low after all that time so you plugged it in finally starting the embedded controller?