TX/RX lights blink twice when plugged in, then go off

Hello! I fried my Arduino Nano so I replaced the diode. After doing so, when I plugged it in via USB the rx and tx lights blink twice simultaneously, then the tx light blinks once, and all lights go off. Happens again once I plug it in, but the actual arduino isn't working and the compiler won't upload programs onto it.

Any ideas?

Cheers