Laptop screen and graphycs card won't work.

# My conondrom:

My laptop's (Lenovo Y540) graphycs card (gtx 1660ti) stopped working. I tried to repair it by cleaning my laptop after three years and reaplying new thermal paste, but it sadly didnt help, it got even worse, now my laptop screen is completely dim. At good light with right angle I can see areas with high contrast, like input for password or discord startup icon a little. I tried plugging my laptop to separate monitor and it only works seldomly (usually after month+ time I didnt touch the laptop) and only lasts for few minutes, after that my graphycs card gives up and I have no way of controlling my laptop. Also my battery is in dire need of replacement as its so bumped up I can hardly close the lid. Tho i did plugged battery off and run with just cable power and it didnt help, so I will buy new battery if I manage to fix these other two problems. Any advice on what to do? I thought that graphycs card had some thermal issues but both ventilators are working and heat pipes are pretty warm too. But I got a feeling that it get way too hot way too fast maybe. Like I am just in windows with everything closed but laptop seems to get pretty hot anyways. Also I dont have integrated graphycs driver, I dont remember now if I didnt have it from the beginning or if I uninstalled it while trying to repair graphycs card(It showed that my dedicated graphycs card had some issue in device manager(error 43 or smth like that) - did look it up back then and usually solutions included reinstalling graphycs drivers and cleaning, which I tried. Anyway my screen had a lot green vertical stripes. Then as mentioned after trying to clean the laptop the screen just went completely dim.

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Any advice please?