MegaShark

No. Because there is no way to fix modern Qualcomm-based phones without Sony factory equipment, like in case of some MTK-based phones. Without service software using proper emergency loader we can do nothing.

So something changed between the Xperia TX (2012) and the Xperia XA2 Ultra (2018), is that it?

You are right, my bad. That means the answer for your problem is only one - main board swap.

Because being identified as qhusb_dload, as in the first post, differs from being identified as QUSB_BULK? Is that it?

 

P.S.

Your phone is Mediatek-based phone, it has not much in common with Xperia TX, a Qualcomm-based product from Sony.

 

Sony Xperia XA2 Ultra runs on a Qualcomm Snapdragon 630 processor.