Disk Utility (Recovery Mode): Cursor stuck on loading (spinning wheel)

I was trying install a new MacOS in recovery mode because my iMac won't startup (stuck on the Apple logo). I needed to open Disk Utility because I needed to do a partition. However, when I open the Disk Utility in recovery mode, the mouse cursor is stuck on loading. I have reset the NVRAM and PRAM, tried starting in Safe Mode (stuck on Apple logo again), and I have also tried both Online Recovery and Recovery partition (same thing happened). My iMac model is 2014, 21.5 inch.

Any suggestions?