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 Power/Volume- at the same time for 30 seconds. Result: It makes the recovery screen appear for less than a second (during that split second I can move the cursor with Volume+/-), then the screen turns black, then recovery for a split second again, then this boot-loop:

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

Pressing the same Volume-/Power during the earlier "white Google+unlocked lock on black background" screen results also results in the same boot-loop.

During all of these phases (animation, recovery, boot-loop), running adb logcat from my connected computer only shows waiting for device.

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