In a nutshell, GE's credit rating is now too low for big financial institutions to invest in, as they all adhere to a certain level of credit rating which they will not go below. This is nothing short of a disaster for GE, which now has to essentially support itself outside the credit market.
https://www.barrons.com/articles/ges-credit-rating-was-just-cut-by-moodys-1541014710