Can I update rooted sgh-i537 to marshmallow? I use an AT&amp;T Galaxy S4 Active (SGH-I537) as my current phone, but I just rom'd my husband's old Note 2 to 5.0.2 and am loving it (mostly because no Google play/Samsung crap/AT&amp;T bloatware). My Active is 5.0.1 right now and I naturally cannot update due to root. I also intend to acquire a new phone by Christmastime (yay Christmas money!), and I have the Note if I brick/fubar this one.

I'm wanting to update to Marshmallow, but I'm getting overwhelmed by all the "tutorials" and stuff online. Most will remove my root, the rest seem to be for Lollipop. Nothing for Marshmallow. 

Can anyone point me to a rom I can flash with, or another way to update and not lose root -- or at least, not have a huge pita to go through to re-root? (Would Kingo root work for it? I believe I used towelroot, but it's been almost two years now.)
You cant update to Android 6 conventionally, nor us a custom rom as the SGH i537 has a locked bootloader. I too am using said phone with the stock rooted Lollipop 5.01.  Im opting for a newer phone with unlocked bootloader though I love my old SG4 Active.