macbook pro shows battery and lighting symbol on startup

To be clear, is this what you're seeing?

If so, your battery is too low to boot your Mac and needs to be charged. Plug in the power adaptor and see if you can boot.

If this isn't the problem, please post back with more information.

Good luck!

Run an Apple Hardware Test. It may offer a clue:

https://support.apple.com/en-us/HT201257

Ciao.

Very odd! It might be worth resetting the SMC and see if this helps.

Good luck!