2017 MacBook air backlight randomly cuts plus smc issues

i recently got a macbook air for free due to potential liquid damage. the logic board, connectors, ribbon cables etc show no sign of damage or corrosion, but i scrubbed everything with alcohol anyway, including the trackpad board. Right now the machine boots, but the backlight will randomly turn off, independent of physical movement, ruling out a bad connection or cable. Im still not sure about this, since it started happening more often when i started using the trackpad, however it does not respond directly when i click or move my hand in a certain direction, for example. Moving the lid does not change anything. Repeated slaps of the case in multiple locations does not change the frequency or duration of the backlight cuts. Later i noticed that instead of just cutting the backlight, the machine would also cut the screen entirely and show the lock screen in a similar fashion and frequency of the backlight cuts, as if its repeatedly receiving a false signal that the user is away or something. I went into settings and made it so that it would never lock or dim the screen due to inactivity, so now the backlight just cuts randomly and if i move the trackpad and the backlight returns in varying amounts of time. Also, When i set the brightness to any point below 50%, the screen will start flickering, but when i set it to 0% for a couple seconds and then return to 10% brightness for example. the screen will be stable for anywhere in between 1 and 60 seconds. There is no flickering problem at 100% brightness. It is also worth noting that the charger plug LED sometimes does not shine when the machine is powered off, however im not sure if this is default behavior since im not familiar with macs.

The condition seems to improve or at least change a little every time i scrub something with the alcohol lol. What i want to know is where specifically is the problem coming from, so i can focus my troubleshooting efforts. I am thinking SMC/SMC reset, keyboard and trackpad connection, and backlight power circuit. I would also like to know is whether or not it would be worth it to buy new cables, if its a connection/corrosion issue. Thank you.