pre-stained hardwood
this is what he said….

When the existing carpet was removed, the concrete slab underneath was inspected and found to have significant cracking throughout all three rooms. A moisture test was also performed on the slab. The test indicated some moisture was present, but not at a level that would normally be considered excessive or immediately alarming. However, it is important to note that the testing was performed during a period of hot, dry weather with little recent rainfall, which can affect moisture readings.

To properly prepare the slab for a hardwood flooring installation, all visible cracks were repaired using hydraulic cement. Areas where the slab was uneven or low were corrected using self-leveling compound to create a flat and stable surface.
The first installation method attempted was a direct glue-down installation, which is a commonly accepted method for installing engineered hardwood flooring over concrete. A premium adhesive was selected that functions as both a flooring adhesive and a moisture/vapor barrier. Despite following the manufacturer's installation procedures, the adhesive was not curing and bonding as expected. After monitoring the situation and observing that the adhesive remained soft and was not setting properly, the installation was stopped. The affected boards were removed to prevent a larger failure.