iPhone 5s no signal eventhough sim card was changed

So my iphone 5s was working normally, it's new okay? Then suddenly it always shows "No Service" I thought it's because of my location but when I leave the house it's still "No Service". I tried my sim card to my samsung phone and it works there. I cut my sim card my self so I thought that was the problem. Now I bought a new "Nano Sim" it fits perfectly. Now it's still not working in my iphone and shows "Searching.." I tried it to my samsung phone, it's working there. I don't know what is happening in my Iphone, i didn't change anything in the settings but I did a software update. Help please. It's been a week now and what I see still is "Searching.."

Can I connect to wifi or hotspot? Yes

Is it an open line? Yes

Second hand? No Brand New

Up to date? Yes, this happened when i updated my ios

my os is up to date and it doesn't work anymore after my update then i tried to restore the iphone and it says "Your iPhone could not be activated because the activation server is temporarily unavailable. Try connecting your iPhone to iTunes to activate it.........." i tried to connect it to my laptop and it always shows an error

and when I checked for answers in apple support i read this..

"If your iPhone uses a SIM card, make sure that the card is in your iPhone. Even without an active contract, your iPhone might still need the SIM card to activate."

is this the reason why i cannot restore the phone? i don't know what am I going to do please help me :'(