I trasnfered data from one macbookpro to another by firewire cable using migrantion assistant . During the migration process , one of the macbooks drainded out of power . I finished trasnfer second time. second macbook is not booting up now. need help

I transfer data from one 2009 macbookpro which runs yosmite to a newer version using firewire cable.

During the data trasnfer process one of the macbooks lost power due to battery low.

I restarted the process and sucessfully completed the process.

When restarting , I headr lot of beeps fromt he PC and now it is not booting. .....Gray screen wiht apple logo and rotating wheel keeps on for long time.

I tried re-installation but same situation.

What could be wrong.