My Mid 2010 Imac 27" won't boot

Hello,

Yesterday night I was using my Imac in lightroom 11. I then closed the program out and went to Ebay within 50 seconds of exting Lightroom my computer showed a white screen with simikar text to "your imac needs to restart press ay key or it will automatically". It then started up normally up until it froze on the apple logo and after 40 minutes I force shut it down and then tried again to restart it. Then it showed the apple log with a bar underneath it which took about 15 minutes to fill up and then when it did it imediatelly shut back down (hard drive was ramping up it made the chime sound and everything keyboard and mouse got power; then nothing and black screen). Tried another time same thing. Then I unplugged all cords from it for one hour and then put them back.... same thing. Can't get to the apple geek bar till April and this is the compter I use for almost everything. I am typing this on an old barley functional macbook.

I hope somebody can help me find the solution,

Noah

Full Imac Specs: Mid 2010 27"; Intel i7 2600 cpu; AMD Radeon HD6970m 2GB graphics card; 32gb Kingston ram I replaced myself (been installed for 2-3 years); 1TB hard drive

External Devices: Das Mac Keyboard; Logitech optical wireless mouse; Seagate External 4TB Hard Drive; HP Officeject Printer; Olympus Fiio E10 DAC