Global Tech Squad sent computer virus after deactivating firewalls to repair Roku Dallas Texas

i needed help with connecting Roku and found a web site that looked like Roku. After calling John said he needed to connect to my computer to get into my modem to check it for proper operation. I said i just call spoke with phone company and they did not need to do that, he insisted there was an issue with the back end and could only access it thru my computer. After allowing this he seemed to know what to do and found the modem file quickly. after a while we unplug modem, unplug tv etc let sit for a while as i run from room to room to do this, then i find him looking into other files he has no place being and i tell him so. He then proceeds to look at and make comments about my antivirus programs. Then he needs to speak to his manager because after a while nothing was working and his manager i assume said it may be the firewall not allowing things to connect, DUMB me i should have followed my instincts right there. the turns off fire wall on modem and windows, still nothing work then he says we nee few more hours, i say thats crazy, all this to hook up roku no way something not right, I tell him will contact modem company to help set up i do not want to do ant thing else, he says fine and click. I go to close files and a few popups come on sayng computer is infected and in danger this number etc. and screen locks up. I unplug and take it to my computer guy... another life lesson hope someone can learn from this.