This is the normal LineageOS loading screen, which I had until yesterday:

Problem: Since yesterday, only one circle is going from right to left, forever. In other words, it never reaches the 3 circles, and my Nexus 5 has become useless.

After reading Nexus 5 stuck on "flying color dots lollipop" screen after Hard Factory Reset I tried pressing Volume+/Volume-/Power at the same time for 30 seconds. Result: It makes the screen turn black. Pressing the same buttons during the earlier "white Google+unlocked lock on black background" screen results in the same also results in a black screen, followed by this loop:

1. white Google+unlocked lock on black background, for a few second
2. black screen
3. Vibration
4. Back to step 1

Question: How to at least get the content of my Nexus 5's storage memory? Or even fix it if possible?