"Err +/- [ ] Flash" message Nikon D3500 | #nikon #nikonD3500 #photography

Errors I see in my Nikon D3500 View Finder (Left to Right) 

Error Meanings:

Err:  

Error. Press shutter release button again.	O (flashes)	Release shutter. If error persists or appears frequently, consult Nikon-authorized service representative.
Start-up error. Contact a Nikon-authorized service representative.		Consult Nikon-authorized service representative.
Metering error

N (flashes)

Flash has fired at full power. Check photo in monitor; if underexposed, adjust settings and try again.

1. Sandisk 16GB (got with camera)
2. Battery full charged 1230mAh - (Nikon original )
3. camera is in really good condition
4. i never dropped or any scratches 
5. shutter is perfectly fine 
6. no light is blinking while inserting and taking out the memory card and battery
7. flash and manual settings i can see on the viewfinder- changes as i choose them, aperture too
8. takes time to write images - sports mode / continuous shots
9. screen froze while shooting thunder and lightning  
10. this is the 4th time - shutter issue
11. i cleaned lens and that metal ring of camera
12. 
    

========need to update few more issues=====

I forget exact term or I can say the word of the unit (motherboard), Nikon Service Center executives provided quick and healthy service, its working fine now. :)