For $29/mo, we provide access to advanced level technicians who will answer your questions on any Macbook board related matter to the best of their knowledge promptly & walk you through how to solve your problem so you can deliver a working board to your customer.
Tried different hard drives with same result. Even tried too both from usb stick, still the same.
After the line appears screen goes black for about 3 sec then just white for 15 sec then black 3 sec then white with apple logo again. this keep looping.
Same with external screen.