No Display And Power And Hard Drive Lights Are Blinkings Dell Latitude E7240 Ultrabook

Chosen Solution

I open the laptop to change the hard drive, but i didnt change anything as the hard i have was a different one. When i turn it back on, only the power light and the hard drive light was blinking with no display.

seremaiakaravaki not uncommon to have this happen without a HDD. Double check your work and get a new HDD and OS and re-evaluate.