Tried to install new GPU and now my computer won't work

Solution
Be careful around that pick as solution button, dudio. It is intended for use by moderators only. That is an extremely low-grade PSU. I would recommend upgrading it to a 550W SeaSonic unit, because it can't even handle the 980 Ti to begin with. That will also fix your problem, as it could be due to the Ti drawing too much wattage from the PSU/triggering something. Worth the upgrade even if you still are having problems imo. This is a great unit for the price: https://pcpartpicker.com/product/bkp323/seasonic-focus-plus-gold-550w-80-gold-certified-fully-modular-atx-power-supply-ssr-550fx
Be careful around that pick as solution button, dudio. It is intended for use by moderators only. That is an extremely low-grade PSU. I would recommend upgrading it to a 550W SeaSonic unit, because it can't even handle the 980 Ti to begin with. That will also fix your problem, as it could be due to the Ti drawing too much wattage from the PSU/triggering something. Worth the upgrade even if you still are having problems imo. This is a great unit for the price: https://pcpartpicker.com/product/bkp323/seasonic-focus-plus-gold-550w-80-gold-certified-fully-modular-atx-power-supply-ssr-550fx
 
Solution