AIO more like AIU - workplace notice and transfer

today is my last day in my current department at my current job. On Monday, I am transferring departments and start with a whole new part of the business. My work computer would not turn on this morning and IT cannot do anything if the computer is not on. It was rebooting/resetting for two hours and I have already delegated off all off my work / all of my tasks, I handed off all the stuff I needed to hand off, and I turned in everything I needed to turn in. My boss is trying to tell me that me leaving early will disrupt my transfer so I emailed HR and let them know what’s going on and now I have a paper trail, but he’s still arguing with me over text telling me I need to complete my shift. Does HR really care if I complete the last four hours of my last shift with my old department before starting my new job with my new department, especially due to a technical issue?