Problem landing interviews through the regular recruiting channels

Good afternoon,

I am currently employed as an analyst in a boutique S&T firm in Scandinavia. This is my first job after handing in my MSc dissertation this fall at a semi-target UK school (Warwick/Imperial). However, I am already seeing first hand how people are being laid off and how the industry is changing because of AI/automation/MIFID2 etc. and I cannot see myself having a future in sales. Two of my mentors (who are retiring in 1 and 3 years) have advised me to jump ship before I get stuck here and I am now out looking for other options.

I believe I have a fairly decent network for my age, as I got to know plenty of people during last recruitment season, and have reached out to a dozen of them since February. Despite getting in contact with MDs and VPs, having them send my resume to HR I have been unsuccessful landing any interviews for one of these two reasons:
1. I am trying to move land a M&A gig but HR seems to look at me like an S&T guy despite only having 8 months of experience.
2. Some bullshit reason like "high school grades aren´t stellar", which makes me question if something else is wrong. My cumulative GPA was B for undergrad and A for masters, both in Finance.
I know my resume and cover letter are up to par, and for the last jobs I have had professionals review it before I sent it off. I have also helped friends write cover letters to land these similar jobs last summer.

I seem to fall between two chairs because I am moving from S&T to M&A, meaning my experience with derivatives is worth next to nothing. Seeing that I have started working I cannot apply for grad-schemes because they are often times reserved for students.

Has anyone been in a similar situation? How did you solve it?