  The search strategy or the finding of new effects for heavy neutrinos often
relies on their different decay channels to detectable particles. In particular
in this work we study the decay of a Majorana neutrino with interactions
obtained from an effective general theory modeling new physics at the scale
$\Lambda$. The results obtained are general because they are based in an
effective theory and not in specific models. We are interested in relatively
light heavy Majorana neutrinos, with masses lower than the $W$ mass
($m_N<m_W$). This mass range simplifies the study by reducing the possible
decay modes. Moreover, we found that for $\Lambda\sim 1$ T$e$V, the neutrino
plus photon channel could give explanation to different observations: we
analyze the potentiality of the studied interactions to explain some
neutrino-related problems like the MiniBooNE and SHALON anomalies. We show in
different figures the dominant branching ratios and the decay length of the
Majorana neutrino in this approach. This kind of heavy neutral leptons could be
searched for in the LHC with the use of displaced vertices techniques. \
