Crimson Sentry maple planted about 5 years. never grew an inch i’d say. last year the leaves were tiny. miniscule. a lot of the branches seem to be brown under the bark- would i be foolish to leave it or should i replace it. photo below seems to show a bit of green under bark but the branchlets are predominantly dead
Most likely this is caused by a poor root system to start with, overly deep planting or heavy wet soil, or a combination.
The tree could be lifted and moved before bud break, or lifted and re-planted but set higher if this turns out to be the problem when it is dug up.
Like all young trees, it should be kept free of grass around its base for at least one metre diameter for five years.
And it might be too weak to survive.