Need some help (Laptop's onboard HDMI won't work)

Hi, i have a Thinkpad E590 with an Intel i5 8265u and Intel UHD 620 graphics, I don't have the Radeon graphics card, only the intel iGPU.The first time I tried to install macOS Catalina, almost everything worked fine, except the iGPU wasn't performing well (the famous only 7MB of VRAM), I already fixed that. But the onboard HDMI didn't work before the fox neither after it.The USB-C display port works just fine (well, almost), I have a Thinkpad USB-C dock (fist gen) and the USBs work, the gigabit ethernet also works it gives video and audio and it charges the laptop.The only flaws I have are that:The onboard HDMI won't work no matter what, I already tried a lot of tutorials in hopes to fix this, but none worked. The symptoms are like the ones described on the tutorials though: when I connect the HDMI, the system lags badly and no signal comes through the HDMI, then, after a while the system goes back to normal, but without HDMI video.Video through the DisplayPort on the dock works, the audio kinda works. It does sound, but always at maximum volume and I can't change the volume from the slider as it doesn't have one. This also happens with the dock's minijack, it will give audio, but always at max volume and without the ability of changing it.

Thank you in advance