So my new computer that i built still will not turn on whatsoever, wont even showcase anything on the screen, now this is making me mad since it cost me around 1000$ to buy all the shit to build it. And all the computer shops want to charge me $150 to look at each individual piece. Any help would be appreciated

ASRock z270 4LGA 1151 6GB 3.1 ATX
Intel Core i5-7500
850W Power Supply
2 4GB DDR4
GIGABYTE GTX 1050Ti