Last week my alarm went off in the middle of the night. After clearing the 1st floor I realized my alarm was tripped in the basement at one of the windows....turned out to be a weak connection but can anyone advise on some tips how is best to enter a basement when there’s a potential threat down there. I was unsure how to proceed down the steps safely.

Awesome. I’ll take a look. Thank you

A few years ago our alarm went off at 2am! GLASS BREAK ALAEM GLASS BREAK ALARM GLASS BREAK ALARM!!! My wife and I did exactly like we have trained to do:

1. We have no kids so we jump behind the bed and point our handguns at the doorway.
2. ADT called 911, they called back on the cordless phone, completely illuminating the bedroom!
3. Wife jumps up to turn off the bathroom light, I flag her with my G19.
4. I jump up to turn phone light off, wife flags me with her G43.
5. I decided that bumping my mag release and dumping the full mag on the floor is what I should do next. So I do that.
6. Wife hands me my full mag off the floor, I attempt to insert it in the mag well, upside down, which seemed like a decent plan at the time.
7. I get my mag back in, paint a green laser on the livingroom wall and declare: "Next MFer thru the door gets shot." It made sense at the time, it didn't 5 seconds later.
8. S.O. deputy shows up and I watch him clear every room, until he found the pan that fell off the stove onto the tile floor, setting off the alarm.

Our plan got some major reworks after that.

Even in my own house single man CBQ is not a thing I'd do, unless it was a must to save a child etc. In your case you cleared to main floor and the basement was left to do. Cover the door and call 911. Let the cops arrive in mass and do it for you.
True story. A few years go a neighbor, a single older guy, woke up around 2AM to the sound of glass breaking. He grabbed his pistol pointed it at his bedroom door and called 911. He stayed on the phone the entire time. Foot steps came down the hall to his bedroom door. He shot the intruder. The police arrived and investigated. No charges were filed against my neighbor.
My neighbor was not acquainted with the intruder and had no idea why the guy broke into his house and came to his bedroom. My neighbor didn't feel safe returning to his home after that. He didn't return and and put the house on the market. The house sold relatively quickly.
Out of respect for my former neighbor I didn't use his name. This is a true story.