macbook software update failing and i am going insane

Hi,for the past 2 days i ve been going crazy over this problem i am having with my mackbook air, i recntly got a 2019 13 inch model and i basically factory reset it wyping the disk and reinstalling os,it booted in mac os mohave 10.14.6 and ive been trying evr since to update it to sonoma but each time the download is doneand it says the mac is about to reboot to install it screen may turn off up to a min it does not ,it just goes black for a second and then boots back into mojave without even a failed to install promt,it just acts like nothing happened and then ask to install it again. At this point i ve checke for evrything, i dont have antivirus or storage problems since essentially it s a blank mackbook without any apps ,i tried to install a combo update after realising that i have a security update for 10.14.6 that does almost the same thing but this time i do get a promt that an error occured and it sends me to disk startup to boot it again but it didnt work,i tried updating to a previous version like big sur hoping it was too big of a leap and that even tho evrywere i checked it said its compatible maybe it was not but nope exact same thing as sonoma i cnt boot it from a usb cuz i only have usb c ports(idiotic design from apple) i dont know what else to do it seems like no one had on the entire the same prob so i am here after the 12 th try hoping somebody has a fix.