CRJ-900 Captain reported inadvertently discharging an engine squib during preflight for the first flight of the day. The aircraft was removed from service for repairs.

Narrative

The event happened at ZZZ; Aircraft X; on Date. We got to the plane early; like XA:40 - CA (Captain) pilot monitoring; FO (First Officer) pilot flying; Name. l got to the flight deck; dark cockpit FFOD (First Flight of the Day). First; l checked the log can for any write-ups; then ground power on; battery master on; wait 30 seconds before l did fire test; fire test ok. Then; battery voltage check. l started the APU after electrical power up was established. l started my flow to do FFOD test on the overhead panel. When l was done with the overhead panel; l moved down with my flow to the glare shield panel to do the stall test. It was dark. l did see well. l selected the right guard button and by accident. l selected LH fire push button; then after that l selected the flight control synoptic page. l started looking up the overhead panel to continuous ignition for the stall test; then l realized my mistake as nothing happened. At this point the FO came back from doing the walk around. l told him l screwed up. l hit the fire push button; then l armed the squib. He said what you going to do? l said l will call Maintenance right away; and also pulled the QRH for L Eng Squib caution message.l was calling Maintenance Control. l spoke with Name 1 first. l explained the situation; what happened. l said l got a L ENG SQB caution message. He said do a power reset. l said could you please stay on the line while l did the power reset. He said call me back when done. He hung up. l did shut down the APU; as well [as the] ground power and battery master switch. Then; l pushed the wrong button - the green light button instead [of] the fire push guard. When l established the power back; l called back to Maintenance Control. Name 1 answered the phone and he said right away hold on; l will transfer you to Name 2. Name 2 then asked me what happened. l explained to him l was doing FFOD test. l pushed by accident the LH FIRE push button instead of the stall test button. He said this is very common on first flight of the day. l heard what he said; l said ok. l got an ED1 L ENG SQB caution message and now an ENG BTL 1 LO caution message and ENG BTL 2 LO. l said on the power reset l misunderstood Name 1. My mistake was that l pushed the green light button on both bottles. Name 1 hung up so l was not walked through the process over the phone. l am trying to help but l screwed up myself. Name 2 said don't feel bad; don't beat up yourself; we are humans; we all make mistakes. l said to Name 2 now l realize that the fire push is still in and HYD Green SOV is closed in an advisory message. He told me yes; push the LH fire push button. l did; then HYD SOV opened. We were on the phone all the time. Also; l said to Name 2; if the bottles are gone; then l know for a fact we are not going anywhere. He said you are right; Name 3; not for a while. l said l am sorry Name 2; l had been here [a few years] between the CRJ200 and CRJ900 and this had never happened to me during a FFOD test procedure. It is the first time in my career and it won't happen again. You learn from mistakes. This is a lesson learned for me for the rest of my career. He said don't worry; this happens once in [a] while; l [have] seen it before in my [30+] years; don't feel bad. l said l feel sorry for my FO and myself. It is a go home day for both; we always want a good plane or no delays and broken planes on the last day. The event occurred from inadvertent deviation from the SOP or Company Policies; for not paying attention on what you [are] doing; not focusing on tasks properly; not looking up carefully for which button you are pushing or executing; not having the best communication with Maintenance Control over the phone; [and] not taking time to think and process the information provided by Maintenance Control. The best suggestion l will like to provide to prevent this in the future is to adhere to the SOP; FOM; and CFM. Put it in practice and don't deviate from them; as well all the core competences applied in your daily routine. The best course of action for me in the future from not occurring again is slow down; don't rush at any moment or any time. Take my time; be proactive with the communications with Maintenance Control for any maintenance issues related to the operations of the flight. l will never do anything again by myself; assuming without having Maintenance Control on the phone; walking me through the process step-by-step until we [are] done. This was a lesson learn for me; which l will record in the back of my mind for the rest of my career.l accept all responsibilities as a Captain. l am [older] and l consider myself mature enough to recognize my mistakes and learn from them. As a human being; we are not perfect pilots; but we all do the best out there for the safety operation of our airlines on the daily basis; adhering the SOP and all company manuals. From my years flying CRJs between Company X and Company Y; this is the first time that this happened to me and it won't happen again for sure. Also; since l [have] been in Company Y; this [was] my first Incident report.