Apple CarPlay Head Unit Problems

Bit of a strange one today. I am by no means any good with electrics but have tried to troubleshoot the problems I have had with my head unit. Firstly, the head unit is an EONON head unit and has been fine since I fitted it three weeks ago, however today I installed jbl door speakers and an Edge subwoofer into my 2004 Fabia vRS. (I also spliced in a boost gauge to the live and ground wires for the head unit to power the back light on the gauge at the same time). It worked great for around 40 minutes of playing until suddenly the head unit and boost gauge went out. The subwoofer still had power straight from the battery. Upon investigation, none of the fuses relevant to the radio or interior had blown at all. Using a multimeter, I discovered that there was no Voltage between the ground and live wires for the head unit. As a test, I have rigged up a live wire with a 25A in line fuse straight from the battery to the splice between the head unit and boost gauge. Interestingly the boost gauge illuminates but the head unit still does not power on. Have I blown the head unit? Strange that the head unit would blow as well as a break in the live wire somewhere at the same time. I don’t know enough to make it make sense so hoping someone will help. Thanks.