Why does the Dell S2340L monitor turn gray and how best to return it to Walmart?

Question

Iron

Computer configuration:
Intel Core i7-4790 processor, OEM
cooler Zalman CNPS10X Optima
motherboard MSI H97M-G43
RAM DIMM DDR3, 8GB, Crucial
HDD 1TB, Western Digital Caviar Blue, WD10EZEX
case ZALMAN Z9 U3, MidiTower, ATX
power supply ATX 750W Corsair CS750 M, Active PFC, 12 cm Fan, Modular, CP-9020078-EU
NVidia GeForce GT 630
Video Card Dell S2340L Monitor, 1920x1080, 8M:1, HDMI, 7ms, IPS, Silver Black [2340-4362]
Bought less than two months ago. The first time the monik turned gray after cleaning with napkins (which are intended for this) - in 1-2 weeks. I turned off the monitor, wiped it, turned it on - it's all gray, phantoms remain after windows and programs - faded "prints" (like it's called a memory effect), in some places heaps of multi-colored pixels, wild illumination. I rubbed very carefully, did not press anywhere.
Turned it on and off, twisted and threw off the settings, checked all the wires - the ailment does not go away. Went to smoke, came back - everything is in order.
The second time this ailment arose when I bent down the monitor, a few days ago. Bang - and all the same. Again he fooled around with him as for the first time, nothing helps. I think I'll smoke it right now and take it back to the store. I return from the balcony - everything is in order.
Who knows what it could be? And what is the best way to contact the store (I bought it in Yulmart), what is better to say? And how long will they keep him there?

Answer 1

I've seen similar symptoms caused by loose/bad DVI cables.