Air carrier Technician reported an inadvertent escape slide deployment while checking an armed aircraft door during a routine overnight check.

Narrative

I was assigned to Aircraft X which was a late arrival Flight ABCD from ZZZ1. This aircraft was due in at XA:16 AND GOING OUT AT XF:25 with a Routine Overnight (RON) and 2 Priority 1 MEL's. I was gathering the info and parts to address this ACFT when I received a phone call on my cell from the Crew chief informing me they had added a second Acft to my workload and I needed to get on it asap as the plan was to move it to a remote parking area. This was a Periodic Service Check (PSC) and when I arrived at the Acft; only one of the crew chiefs was working the acft; he was oiling #2 engine. I forgot the gate code as they had just been changed. When I went inside to get new gate codes I informed the crew chiefs that not enough people assigned to the check and received the ZZZ standard answer we don't have anyone else" I stated then defer the check and heard the standard laughter. I assumed the Crew Chief (CC) working with me had the basic operating weight (BOW) and went by what I was told it was a PS check. I went onto the ACFT TO DO A QUICK WALK THRU as the acft was being moved shortly. The tug was in place as well as one of the move crew in the cockpit. Cause: On my quick walk; thru I observed the crew OXY at 1330 psi; 2 rolls of paper were required; tray table at row 4 was taped up. This was an effort to see what supplies and equipment were needed at the remote location to accomplish the check. On the way forward I decided to take a peek at one of the door assist bottles to see if I needed to drag a nitrogen cart with me. That's when I blew the slide. I thought the door was disarmed but the handle jumped as soon as I started to move the handle. I closed the handle but too late as I heard the slide deploy. The repair required a slide change; bottle change; the door assist bottle was ok and remained charged. I was tired on top of this as my mother was having dialysis and had collapsed and was rushed to the ER earlier in the day. I was running on little rest. This was an accident / mistake on my part. Suggestions: The crew chiefs need to give briefings as required; don't rush the mechanics because of lack of planning. It is a very rare thing at ZZZ for the crew chiefs to say no. The work load is extremely large most nights and we are under staffed. It is left up to the mechanics to find spotters or help if needed in most cases. I informed the union on several occasions that it was just a matter of time before something happened at ZZZ."