  This work is a continuation of Paper I [Sharykin et al., 2018] devoted to
analysis of nonthermal electron dynamics and plasma heating in the confined
M1.2 class solar flare SOL2015-03-15T22:43 revealing energy release in the
highly sheared interacting magnetic loops in the low corona, above the polarity
inversion line (PIL). The scope of the present work is to make the first
extensive quantitative analysis of the photospheric magnetic field and
photospheric vertical electric current (PVEC) dynamics in the confined flare
region near the PIL using new vector magnetograms obtained with the
Helioseismic and Magnetic Imager (HMI) onboard the Solar Dynamics Observatory
(SDO) with high temporal resolution of 135 s. Data analysis revealed sharp
changes of the magnetic structure and PVEC associated with the flare onset near
the PIL. It was found that the strongest plasma heating and electron
acceleration were associated with the largest increase of the magnetic
reconnection rate, total PVEC and effective PVEC density in the flare ribbons.
Observations and non-linear force-free field (NLFFF) extrapolations showed that
the magnetic field structure around the PIL is consistent with the
tether-cutting magnetic reconnection (TCMR) geometry. We gave qualitative
interpretation of the observed dynamics of the flare ribbons, magnetic field
and PVEC, and electron acceleration, within the TCMR scenario.
