#include <algorithm>
#include <bitset>
#include <cassert>
#include <cmath>
#include <cstdint>
#include <cstring>
#include <deque>
#include <fstream>
#include <iomanip>
#include <iostream>
#include <limits>
#include <map>
#include <numeric>
#include <ostream>
#include <queue>
#include <random>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <unordered_map>
#include <unordered_set>
#include <vector>

using namespace std;
/// Pragmas ///
/// define ///
#define pii pair<int, int>
#define pll pair<ll, ll>
#define V vector
#define MP make_pair
#define vi vector<int>
#define ff first
#define ss second
#define vl vector<long long>
/// typedef ///
typedef long long ll;
typedef long double ld;
typedef unsigned long long ull;

/// solve ///
// consts
const double PI = acos(-1);
const ll MOD = 1000000007;
const ll MOD2 = 1000000009;
// const int p = 239;
const ll p = 1'000'000;
long long int inf = 1000009;
const int N = 105;
const double eps = 1e-18;
int dx[8] = {1, 0, -1, 0, 1, -1, -1, 1};
int dy[8] = {0, 1, 0, -1, 1, 1, -1, -1};
#define int long long
ll gcd(ll a, ll b) { return b ? gcd(b, a % b) : a; }

ll lcm(ll a, ll b) { return a * (b / gcd(a, b)); }

V<V<char>> g(N, V<char>(N, '#'));

V<V<ll>> dist(N, V<ll>(N, inf));
V<V<pll>> pr(N, V<pll>(N));
V<V<bool>> used(N, V<bool>(N, false));
void bfs(int start_x, int start_y) {
  dist[start_x][start_y] = 0;
  used[start_x][start_y] = true;
  queue<pair<int, pair<int, int>>> q;
  q.push({0, {start_x, start_y}});
  while (q.size()) {
    pair<int, pair<int, int>> vv = q.front();
    pair<int, int> v = vv.ss;
    q.pop();
    for (size_t i = 0; i < 4; i++) {
      if (g[v.ff + dx[i]][v.ss + dy[i]] == '#' ||
          g[v.ff + dx[i]][v.ss + dy[i]] == 'A' ||
          g[v.ff + dx[i]][v.ss + dy[i]] == 'B' ||
          g[v.ff + dx[i]][v.ss + dy[i]] == 'a' ||
          g[v.ff + dx[i]][v.ss + dy[i]] == 'b')
        continue;
      pair<int, int> u = {v.ff + dx[i], v.ss + dy[i]};
      if (dist[u.ff][u.ss] >= dist[v.ff][v.ss] + 1 && !used[u.ff][u.ss]) {
        used[u.ff][u.ss] = true;
        dist[u.ff][u.ss] = dist[v.ff][v.ss] + 1;
        pr[u.ff][u.ss] = v;
        q.push({dist[u.ff][u.ss], u});
      }
    }
  }
}

void rs() {
  dist.clear();
  dist.resize(N);
  for (size_t i = 0; i < N; i++) {
    dist[i].resize(N, inf);
  }
  pr.clear();
  pr.resize(N);
  for (size_t i = 0; i < N; i++) {
    pr[i].resize(N);
  }
  used.clear();
  used.resize(N);
  for (size_t i = 0; i < N; i++) {
    used[i].resize(N, false);
  }
}

void solve() {
  rs();
  int n, m;
  cin >> n >> m;
  int start_xA, start_yA, start_xB, start_yB;
  for (size_t i = 1; i <= n; i++) {
    for (size_t j = 1; j <= m; j++) {
      char x;
      cin >> x;
      g[i][j] = x;
      if (x == 'A') {
        start_xA = i;
        start_yA = j;
      } else if (x == 'B') {
        start_xB = i;
        start_yB = j;
      }
    }
  }

  bfs(start_xB, start_yB);
  int distB = dist[1][1];
  rs();
  bfs(start_xA, start_yA);
  int distA = dist[1][1];
  rs();
  if (distA < distB) {
    bfs(start_xA, start_yA);
    pll pos = {1, 1};
    while (pos != make_pair(start_xA, start_yA)) {
      g[pos.ff][pos.ss] = 'a';
      pos = pr[pos.ff][pos.ss];
    }
    rs();
    bfs(start_xB, start_yB);
    pos = {n, m};
    while (pos != make_pair(start_xB, start_yB)) {
      g[pos.ff][pos.ss] = 'b';
      pos = pr[pos.ff][pos.ss];
    }
    for (size_t i = 1; i <= n; i++) {
      for (size_t j = 1; j <= m; j++) {
        cout << g[i][j];
      }
      cout << '\n';
    }
  } else {
    bfs(start_xB, start_yB);
    pll pos = {1, 1};
    while (pos != make_pair(start_xB, start_yB)) {
      g[pos.ff][pos.ss] = 'b';
      pos = pr[pos.ff][pos.ss];
    }
    rs();
    bfs(start_xA, start_yA);
    pos = {n, m};
    while (pos != make_pair(start_xA, start_yA)) {
      g[pos.ff][pos.ss] = 'a';
      pos = pr[pos.ff][pos.ss];
    }
    for (size_t i = 1; i <= n; i++) {
      for (size_t j = 1; j <= m; j++) {
        cout << g[i][j];
      }
      cout << '\n';
    }
  }
}

signed main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
  freopen("input.txt", "r", stdin);
  freopen("output.txt", "w", stdout);
  int t = 1;
  cin >> t;
  while (t--)
    solve();
  return 0;
}