Your parents should not be homeowners, period. Either they don’t have the money to maintain their home properly, in which case forcing a HELOC and repairs will be only a stop-gap measure until they fall behind again*; or they are not psychologically suited to manage all of the obligations that come with homeownership, in which case forcing a HELOC and repairs will be only a stop-gap measure until the house falls apart again.
Your continued financial support is therefore hurting them. They may have the ability to change somewhere buried deep inside them. But why bother when you are always there to rescue them when things get hard? The more you give them financially, the more you jump in to rescue them and tell them what they need to do, the more you are treating them like children who cannot be expected to be capable of taking care of themselves. And people tend to live up or down to the expectations you set for them.
What that means is that your continued support is for your benefit, not theirs. It makes you feel good, or it assuages the guilt of watching your parents struggle, or it meets family expectations that you were raised with or avoids pressure/guilt trips they might put on you if you don’t help, or whatever. I don’t know what the actual emotional driver is, but it’s important to recognize that your response is about you, not them.
If you truly want to do what’s best for them, you need to raise your expectations for their behavior. Treat them like grown adults who are competent to make their own decisions, not children who can’t be left unsupervised. Give them your advice and emotional support, but do not accept responsibility for their choices, and do not shield them from the consequences of making poor decisions - that is the only way some people can learn.
I also don’t think you understand the gravity of the housing situation. It is currently uninhabitable by any US standards. If your parents were landlords, they could be sued and have the rent withheld until the repairs are made. If your parents were trying to rent it as Section 8 housing - which does not tend to be super-high-standard housing - they would be laughed out of the office. If they try to sell it and the buyer needs an FHA or VA mortgage, they will not be able to sell it, and it is questionable whether any normal mortgage company will issue a loan; they might end up being forced to take a lowball offer from a “we pay cash for houses” guy. You will not get the HELOC if you get an appraiser that is paying attention; obviously, I can’t say what kind of appraiser you will get, but if that is the plan, can you afford to take that risk? In addition, if the HELOC or refinance request lets the current mortgage holder know about the state of the house, they could call the existing mortgage, and your parents could lose the house anyway.
I’m not saying this to be mean. It just seems like it’s not only your parents’ perspective that is warped, but your own as well. Your parents have one single asset - their house - and yet they have not done the most basic things to take care of it - and they still do not see the need to do so. You also apparently don’t see the issue with just “a little” electrical issue and “a little” long-term leaking. In addition, you donated $60k to “save” them, and then immediately got sucked into donating another $10k, which you apparently paid without batting an eye. That tells me you have the same issues and blindspots that your parents do - they expect unreasonable things from you, and you expect the same unreasonable things of yourself, and no one even realizes exactly how unreasonable, how far out of the norm, those expectations are.
So before you dive in even deeper to fix more of your parents’ problems for them, please take a look at yourself - what is driving you? Is that reasonable? Is it in your own long-term interests? Is it in your parents’? If you continue to save them, how will they learn to save themselves - and why should they even try?
*Don’t bullshit yourself by saying they can afford it if they cut back in other areas. They have had decades to cut back in those areas to avoid getting into this situation in the first place. If they had either the desire or the psychological ability to do so, they would have.