Why does my phone not turn on (or show display) but does vibrate when recieving notifications? (Instead it shows a dark blue screen! I took it to a shop and they told me my phone has no fix! Is this true??!)

i paid $50 to get my screen replaced because it was crack for about 2 months and then one week later after Getting my screeen fixed, well first I got a "virus" warning saying my phone has one (but I wasn't sure because it's so rare for an iPhone to get a virus) i ignored it then the next night I think i got a dark pink screen on my phone when I tried to turn it on and have access on my phone but I couldn't . Minutes past and I check my phone and perfect. BUT it happened again the following morning and that time it didn't go back to how it was. I can't use it. PLZ HELP