One of the other ways people seem to be able to fix their credit fast is by enrolling in a creditsweep program. the creditsweep program can work, sometimes, maybe, under the right circumstances for a few select people if done 100% correct and if you are willing to break a few laws and pay for the service upfront in cash or bitcoin. See!, nothing to it.
I do not agree with the secured card info you've provided. They are great tools when used correctly. You can find one with no/small annual fee. The interest rate won't come into play if you pay your balance in full each month. Even if you don't pay in full, the interest on a very low balance is a non-factor. Alomst any credit union will allow you to open an account with as little as $5 and secured card with $300/500. My card is $500 and I never charge more than $150(30%). It takes will power to not max it out. You don;t want to fall back into old habits (if that is what got you into this situation in the first place).
Next, estimate your monthly spending habits for other expenses such as gas, groceries and entertainment. Create a limit, based on your income, of what you can spend in each of the different categories of expenses. For example, if you tend to spend $400 a month on groceries, try to stick to $300 a month on groceries by making changes like buying generic brands, using coupons, and resisting impulse purchases.